This document is in two parts. The first part is this prospectus supplement, which describes the specific terms of this offering and the notes. The second part is the accompanying prospectus, which gives more general information, some of which may not apply to this offering. We urge you to read the entire prospectus and this prospectus supplement, together with the information described under the heading “Where You Can Find More Information” in the accompanying prospectus carefully, including the risk factors set forth under “Risk Factors” in this prospectus supplement and the risk factors incorporated by reference herein.

If the information varies between this prospectus supplement and the accompanying prospectus, you should rely on the information contained in or incorporated by reference in this prospectus supplement.

You should rely only on the information contained in or incorporated by reference in this prospectus supplement and the accompanying prospectus or any free writing prospectus prepared by or on behalf of us. We have not, and the

underwriters have not, authorized anyone to provide you with different or additional information. We are not making an offer to sell these notes in any jurisdiction where the offer is not permitted. You should assume that the information contained in this prospectus supplement, the accompanying prospectus and the documents incorporated herein and therein by reference is accurate only as of its respective date or on the date which is specified in those documents and that any information we have incorporated by reference is accurate only as of the date of the document incorporated by reference. Our business, financial condition, results of operations and prospects may have changed since these dates.

Unless otherwise indicated, all information in this prospectus supplement assumes no exercise by the underwriters of their option to purchase up to an additional $22,500,000 in original principal amount of notes solely to cover over-allotments for a period of 13 days following the date of this prospectus supplement.

The market and industry data contained in this prospectus supplement and in documents incorporated herein by reference are based either on management’s own estimates, independent industry publications, reports by

market research firms or other published independent sources, and, in each case, are believed by management to be reasonable estimates.

This prospectus supplement and the accompanying prospectus may contain or incorporate by reference information that includes or is based upon forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995, or the Reform Act. Generally, you can identify these statements because they use words like “anticipates,” “believes,” “will,” “estimates,” “expects,” “future,” “intends,” “plans” or the negative of such terms or similar terms. All statements addressing operating performance, events, or developments that we expect or

anticipate will occur in the future, including statements relating to sales growth, earnings or earnings per share growth, and market share, as well as statements expressing optimism or pessimism about future operating results, are forward-looking statements within the meaning of the Reform Act. The forward-looking statements are and will be based on management’s then-current beliefs and assumptions regarding future events and operating performance and on information currently available to our management, and are applicable only as of the dates of such statements.

Forward-looking statements involve risks, uncertainties and assumptions. Although we do not make forward-looking statements unless we believe we have a reasonable basis for doing so, we cannot guarantee their accuracy. Actual results may differ materially from those expressed in these forward-looking statements due to a number of uncertainties and risks, including the risks described in our Annual Report on Form 10–K for the fiscal year ended March 31, 2007, any risk factors set forth in our other filings with the SEC pursuant to Sections 13(a), 13(c), 14, or 15(d) of the Exchange Act and other unforeseen risks. You should not put undue reliance on any forward-looking statements. We undertake no obligation to update or revise these statements to reflect events or circumstances occurring after the date of such statements.

Our actual results may differ materially from those contemplated by the forward-looking statements for a number of reasons, including the following factors:

This list of factors that may affect future performance is illustrative, but by no means exhaustive. Accordingly, all forward-looking statements should be evaluated with the understanding of their inherent uncertainty. You are advised to consult any further disclosures we make on related subjects in the reports we file with the SEC pursuant to Sections 13(a), 13(c), 14, or 15(d) of the Exchange Act.

PROSPECTUS SUPPLEMENT SUMMARY

ENERSYS

We operate in an extremely competitive industry and are subject to continual pricing pressure.

We compete with a number of major international manufacturers and distributors, as well as a large number of smaller, regional competitors. Due to the globally competitive nature of the industry, we have been subjected to continual and significant pricing pressures. These pricing pressures have prevented us from fully passing increased commodity and other costs through to customers. We anticipate heightened competitive pricing pressure as Chinese and other foreign producers, able to employ labor at significantly lower costs than producers in the U.S. and Western Europe, expand their export capacity and increase their marketing presence in our major U.S. and European markets. Several of our competitors have strong technical, marketing, sales, manufacturing, distribution and other resources, as well as significant name recognition, established positions in the market and long-standing relationships with original equipment manufacturers and other customers. In addition, certain of our competitors own lead smelting facilities which, during periods of lead cost increases or price volatility, may provide a competitive pricing advantage and reduce their exposure to volatile raw material costs. Our ability to maintain and improve our operating margins has depended, and continues to depend, on our ability to control and reduce our costs. We

cannot assure you that we will be able to continue to reduce our operating expenses, to raise or maintain our prices or increase our unit volume, in order to maintain or improve our operating results.

Cyclical industry conditions of our customers have adversely affected and may continue to adversely affect our results of operations.

Our operating results are affected by the general cyclical pattern of the industries in which our major customer groups operate and the overall economic conditions in which we and our customers operate. Both our reserve power and motive power segments are heavily dependent on the end-user markets they serve, such as telecommunications, UPS and electric industrial forklift trucks. A weak capital expenditure environment in these markets has had, and can be expected to have, a material adverse effect on our results of operations.

Our raw materials costs are volatile and expose us to significant movements in our product costs.

We employ significant amounts of lead, plastics, steel, copper and other materials in our manufacturing processes. We estimate that raw materials costs account for over half of our cost of goods sold. Lead is our most significant raw material. The costs of these raw materials, particularly lead, are volatile and beyond our control.

Volatile raw materials costs can significantly affect our operating results and make period-to-period comparisons extremely difficult. We cannot assure you that we will be able to hedge the costs of our raw material requirements at a reasonable level or pass on to our customers the increased costs of our raw materials.

Our operations expose us to the risk of material environmental, health and safety liabilities, costs, and litigation.

In the manufacture of our products throughout the world, we process, store, dispose of and otherwise use large amounts of hazardous materials, especially lead and acid. As a result, we are subject to extensive and changing environmental, health and safety laws and regulations governing, among other things: the generation, handling, storage, use, transportation and disposal of hazardous materials; remediation of polluted soil or groundwater; emissions or discharges of hazardous materials into the ground, air or water; and the health and safety of our employees. Compliance with these laws and regulations results in ongoing costs. Failure to comply with these laws or regulations, or to obtain or comply with required environmental permits, could result in fines, criminal charges or other sanctions by regulators. From time to time we have had instances of alleged or actual noncompliance that have resulted in the imposition of fines, penalties and required corrective actions. Our ongoing compliance with environmental, health and safety laws, regulations and permits could require us to incur significant expenses, limit our ability to modify or expand our facilities or continue production and require us to install additional pollution control equipment and make other capital improvements. In addition, private parties, including current or former employees, could bring personal injury or other claims against us due to the presence of, or exposure to, hazardous substances used, stored or disposed of by us or contained in our products.

Certain environmental laws assess liability on owners or operators of real property for the cost of investigation, removal or

remediation of hazardous substances at their current or former properties or at properties at which they have disposed of hazardous substances. These laws may also assess costs to repair damage to natural resources. We may be responsible for remediating damage to our properties that was caused by former owners. Soil and groundwater contamination has occurred at some of our current and former properties and may occur or be discovered at other properties in the future. We are currently investigating and monitoring soil and groundwater contamination at certain of our properties, and we may be required to conduct these operations at other properties in the future. In addition, we have been and in the future may be liable to contribute to the cleanup of locations owned or operated by other persons to which we or our predecessor companies have sent wastes for disposal, pursuant to federal and other environmental laws. Under these laws, the owner or operator of contaminated properties and companies that generated, disposed of or arranged for the disposal of wastes sent to a contaminated disposal facility can be held jointly and severally liable for the investigation and cleanup of such properties, regardless of fault.

We cannot assure you that we have been or at all times will be in compliance with environmental laws and regulations or that we will not be required to expend significant funds to comply with, or discharge liabilities arising under, environmental laws, regulations and permits, or that we will not be exposed to material environmental, health or safety litigation.

Legislation regarding the restriction of the use of certain hazardous substances in electrical and electronic equipment.

The European Union has directed that new electrical and electronic equipment not contain certain hazardous substances, including lead and cadmium. Because battery accessories and chargers are subject to this directive, our compliance with the directive directly impacts our manufacturing of these products. In addition, certain other jurisdictions

outside the European Union have implemented, or plan to implement, similar restrictions with various compliance dates. We cannot assure you that we will meet all restrictions by the required dates. Inventory obsolescence and our failure to comply could each have an adverse effect on our financial results.

We are exposed to exchange rate risks, and our net income and financial condition may suffer due to currency translations.

We invoice foreign sales and service transactions in local currencies and translate net sales using actual exchange rates during the period. We translate our non-U.S. assets and liabilities into U.S. dollars using current rates as of the balance sheet date. Because a significant portion of our revenues and expenses are denominated in foreign currencies, changes in exchange rates between the U.S. dollar and foreign currencies, primarily the euro and British pound, may adversely affect our revenue, cost of revenue and operating margins. For example, foreign currency depreciation against the U.S. dollar will reduce the value of our foreign revenues and operating earnings as well as reduce our net investment in foreign subsidiaries.

Most of the risk of fluctuating foreign currencies is in our European operations, which comprised over half of our net sales during the last two fiscal years. The euro is the dominant currency in our European operations.

The translation impact from currency fluctuations on net sales and operating earnings in the Americas and Asia regions is minimal, as a substantial majority of these net sales and operating earnings are in dollars or are closely correlated to the dollar.

Foreign currency depreciation will make it more expensive for our non-U.S. subsidiaries to purchase certain of our raw material commodities that are priced globally in U.S. dollars, while the related revenue will decrease when translated to U.S. dollars. Significant movements in foreign exchange

rates can have a material impact on our results of operations and financial condition. We periodically engage in hedging of our foreign currency exposure, but cannot assure you that we can successfully hedge all of our foreign currency exposure or do so at a reasonable cost.

Our international operations may be adversely affected by actions taken by foreign governments or other forces or events over which we may have no control.

We currently have significant manufacturing and distribution facilities outside of the U.S., including in the United Kingdom, France, Germany, China, Mexico, Poland, Czech Republic, Spain, Italy and Bulgaria. We may face political instability and economic uncertainty, cultural and religious differences and difficult labor relations in our foreign operations. We also may face barriers in the form of long-standing relationships between potential customers and their existing suppliers, national policies favoring domestic manufacturers and protective regulations including exchange controls, restrictions on foreign investment or the repatriation of profits or invested capital, changes in export or import restrictions and changes in the tax system or rate of taxation in countries where we do business. We cannot assure you that we will be able to successfully develop and expand our international operations and sales or that we will be able to overcome the significant obstacles and risks of our international operations.

Our failure to introduce new products and product enhancements and broad market acceptance of new technologies introduced by our competitors could adversely affect our business.

Many new energy storage technologies have been introduced over the past several years. In addition, recent advances in fuel cell and flywheel technology have been introduced for use in selected applications that compete with the end uses for industrial batteries. For certain important and growing markets, such

as aerospace and defense, lithium-based battery technologies have large and growing market share. Our ability to achieve significant and sustained penetration of key developing markets, including aerospace and defense, will depend upon our success in developing or acquiring these and other technologies, either independently, through joint ventures or through acquisitions. If we fail to develop or acquire, and manufacture and sell, products that satisfy our customers’ demands, or we fail to respond effectively to new product announcements by our competitors by quickly introducing competitive products, then market acceptance of our products could be reduced and our business could be adversely affected. We cannot assure you that our lead-acid products will remain competitive with products based on new technologies.

We may not be able to adequately protect our proprietary intellectual property and technology.

We rely on a combination of copyright, trademark, patent and trade secret laws, non-disclosure agreements and other confidentiality procedures and contractual provisions to establish, protect and maintain our proprietary intellectual property and technology and other confidential information. Certain of these technologies, especially in thin-plate pure-lead — TPPL— technology, are important to our business and are not protected by patents. Despite our efforts to protect our proprietary intellectual property and technology and other confidential information, unauthorized parties may attempt to copy or otherwise obtain and use our intellectual property and proprietary technologies.

Relocation of our customers’ operations could adversely affect our business.

The trend by a number of our North American and Western European customers to move manufacturing operations and expand their businesses into Asia and other low labor-cost markets may have an adverse impact on our business. As our customers in traditional manufacturing-based industries seek to move their manufacturing operations to lower-cost

territories, there is a risk that these customers will source their energy storage products from competitors located in those territories and will cease or reduce the purchase of products from our manufacturing plants. We cannot assure you that we will be able to compete effectively with manufacturing operations of energy storage products in those territories, whether by establishing or expanding our manufacturing operations in those lower-cost territories or acquiring existing manufacturers.

We may fail to implement our cost reduction initiatives successfully and improve our profitability.

We must continue to implement cost reduction initiatives to achieve additional cost savings in future periods. We cannot assure you that we will be able to achieve all of the cost savings that we expect to realize from current or future initiatives. In particular, we may be unable to implement one or more of our initiatives successfully or we may experience unexpected cost increases that offset the savings that we achieve. Given the continued competitive pricing pressures experienced in our industry, our failure to realize cost savings would adversely affect our results of operations.

Quality problems with our products could harm our reputation and erode our competitive position.

The success of our business will depend upon the quality of our products and our relationships with customers. In the event that our products fail to meet our customers’ standards, our reputation could be harmed, which would adversely affect our marketing and sales efforts. We cannot assure you that our customers will not experience quality problems with our products.

We offer our products under a variety of brand names, the protection of which is important to our reputation for quality in the consumer marketplace.

We rely upon a combination of trademark, licensing and contractual covenants

to establish and protect the brand names of our products. We have registered many of our trademarks in the U.S. Patent and Trademark Office and in other countries. In many market segments, our reputation is closely related to our brand names. Monitoring unauthorized use of our brand names is difficult, and we cannot be certain that the steps we have taken will prevent their unauthorized use, particularly in foreign countries where the laws may not protect our proprietary rights as fully as in the U.S. We cannot assure you that our brand names will not be misappropriated or utilized without our consent or that such actions will not have a material adverse effect on our reputation and on our results of operations.

We may fail to implement our plans to make acquisitions.

As part of our business strategy, we have grown, and plan to continue growing, by acquiring other product lines, technologies or facilities that complement or expand our existing business. We may be unable to implement this part of our business strategy and may not be able to make acquisitions to continue our growth. There is significant competition for acquisition targets in the industrial battery industry. We may not be able to identify suitable acquisition candidates or negotiate attractive terms. In addition, we may have difficulty obtaining the financing necessary to complete transactions we pursue. In that regard, our credit facilities restrict the amount of additional indebtedness that we may incur to finance acquisitions and place other restrictions on our ability to make acquisitions. The amounts we may pay for acquisitions are subject to limits on individual transactions and aggregate limits over the term of the credit facilities. Our ability to incur additional indebtedness also is restricted such that any significant acquisitions that could not be financed through cash generated from operations would need to be financed through issuance of additional company common stock. Exceeding any of these limitations would require the consent of our lenders. Our failure to execute our acquisition strategy could have a material adverse effect on our business. We cannot assure you that our acquisition strategy will be successful.

Any acquisitions that we complete may dilute the ownership interest in EnerSys of our existing stockholders, may have adverse effects on our financial condition and results of operations and may cause unanticipated liabilities.

Future acquisitions may involve the issuance of our equity securities as payment, in part or in full, for the businesses or assets acquired. Any future issuances of equity securities would dilute the ownership interests of our existing stockholders. In addition, future acquisitions might not increase, and may even decrease, our earnings or earnings per share and the benefits derived by us from an acquisition might not outweigh or might not exceed the dilutive effect of the acquisition. We also may incur additional debt or suffer adverse tax and accounting consequences in connection with any future acquisitions.

The failure of critical computer systems could seriously affect our sales and operations.

We operate a number of critical computer systems throughout our business that can fail for a variety of reasons. If such a failure were to occur, then we may not be able to sufficiently recover from the failure in time to avoid the loss of data or any adverse impact on certain of our operations that are dependent on such systems. This could result in lost sales and the inefficient operation of our facilities for the duration of such a failure.

Our significant indebtedness could adversely affect our financial condition.

As of December 30, 2007, we had $431.9 million of total consolidated debt, and as of April 27, 2008, we had $442.2 million of total consolidated debt. This level of debt could:

The notes are unsecured; effectively subordinated to our secured indebtedness to the extent of the value of the collateral securing such indebtedness; and structurally subordinated to all existing and future claims of our subsidiaries’ creditors, including trade creditors and preferred stock of our subsidiaries.

The notes will be general senior unsecured obligations of the company, ranking equal in right of payment with all of its existing and future senior unsecured indebtedness, senior in right of payment to all of its existing and future subordinated indebtedness, structurally subordinated in right of payment to all of (i) the existing and future indebtedness and other liabilities of its subsidiaries and (ii) preferred stock issued by its subsidiaries to the extent of its liquidation preference; and effectively subordinated to any of its existing and future secured indebtedness to the extent of the value of the collateral that secures it. However, the indenture for the notes does not restrict us or our subsidiaries from incurring additional debt or other liabilities, including secured debt. In the event of our insolvency, bankruptcy, liquidation, reorganization, dissolution or winding up, we may not have sufficient assets to pay amounts due on any or all of the notes the outstanding.

None of our subsidiaries has guaranteed or otherwise become obligated with respect to the notes. Our right to receive assets from any of our subsidiaries upon its liquidation or reorganization, and the right of holders of the notes to participate in those assets, is structurally subordinated to claims of that subsidiary’s creditors, including trade creditors. As of December 30, 2007, our subsidiaries had $431.9 million aggregate principal amount of indebtedness outstanding (including $353.2 million of indebtedness of EnerSys Capital Inc. outstanding under our existing credit facilities) and approximately $603.9 million of other liabilities outstanding (excluding intercompany liabilities and liabilities of the type not required to be recorded on the balance sheet in accordance with GAAP). As of April 27, 2008, our subsidiaries had $442.2 million aggregate principal amount of indebtedness outstanding (including $362.6 million of indebtedness of EnerSys Capital Inc. outstanding under our existing credit facilities) and approximately $593.1 million of other liabilities outstanding (excluding intercompany liabilities and liabilities of the type not required to be recorded on the balance sheet in accordance with GAAP). In addition, if the new credit facilities are guaranteed by the credit facility guarantors and secured by the credit facility collateral, then the notes will be structurally subordinated to the new credit facilities and will be effectively subordinated to

the new credit facilities to the extent of the value of the credit facility collateral securing such facilities. Furthermore, none of our subsidiaries is under any obligation to make payments to us, and any payments to us would depend on the earnings or financial condition of our subsidiaries and various business considerations. Statutory, contractual or other restrictions may also limit our subsidiaries’ ability to pay dividends or make distributions, loans or advances to us. For these reasons, we may not have access to any assets or cash flows of our subsidiaries to make payments on the notes.

If our subsidiaries do not make sufficient distributions to us, we will not be able to make payment on the notes. In addition, the structural subordination of the notes to certain of our subsidiaries’ liabilities may limit our ability to make payment on the notes.

We are a holding company with no business operations, sources of income or assets of our own other than our ownership interests in our subsidiaries. Because all our operations are conducted by our subsidiaries, our cash flow and our ability to make payments on the notes, is dependent upon cash dividends and distributions or other transfers from our subsidiaries. The ability of our subsidiaries to pay cash dividends or make distributions to us is limited by the terms of our existing credit facility. In addition, any payment of dividends, distributions, loans or advances by our subsidiaries to us could be subject to restrictions on dividends or repatriation of earnings under applicable local law, monetary transfer restrictions and foreign currency exchange regulations in the jurisdictions in which our subsidiaries operate, and any restrictions imposed by the current and future debt instruments of our subsidiaries.

The notes will be structurally subordinated to all existing or future liabilities of our subsidiaries, including any preferred stock issued by our subsidiaries. In the event of a bankruptcy, liquidation, dissolution, reorganization or similar proceeding with respect to any subsidiary, we, as a common

equity owner of such subsidiary, and, therefore, holders of our debt, including holders of the notes, will be subject to the prior claims of such subsidiary’s creditors, including trade creditors.

We may incur additional indebtedness ranking equal to the notes.

If we incur any additional debt that ranks equally with the notes, including trade payables, the holders of that debt will be entitled to share ratably with you in any proceeds distributed in connection with any insolvency, liquidation, reorganization, dissolution or other winding-up of us. This may have the effect of reducing the amount of proceeds paid to you, if any.

The sale of common stock concurrently with this offering, future issuances of common stock and hedging activities may depress the trading price of our common stock and the notes.

The sale of common stock concurrently with this offering and any issuance of equity securities after this offering, including the issuance of shares upon conversion of the notes, could dilute the interests of our existing stockholders, including holders who have received shares upon conversion of their notes, and/or could substantially decrease the trading price of our common stock and the notes. We may issue equity securities in the future for a number of reasons, including to finance our operations and business strategy (including in connection with acquisitions, strategic collaborations or other transactions), to adjust our ratio of debt to equity, to satisfy our obligations upon the exercise of outstanding warrants or options or for other reasons.

In addition, the price of our common stock could also be affected by possible sales of our common stock by investors who view the notes as a more attractive means of equity participation in our company and by hedging or arbitrage trading activity that we expect to develop involving our common stock. The hedging or arbitrage could, in turn, affect the

trading price of the notes, or any common stock that holders receive upon conversion of the notes.

Our stock price may be volatile, and your investment in our common stock could decline in value.

The price of our common stock on the New York Stock Exchange constantly changes. Within the last 12 months through May 16, 2008, the last daily reported sale price of our common stock has ranged from $18.01 to $29.51 per share. We expect that the market price of our common stock will continue to fluctuate. Holders of our common stock will be subject to the risk of volatility and depressed prices. Our common stock price can fluctuate as a result of a variety of factors, many of which are beyond our control. The factors described under “Forward-Looking Statements” in this prospectus supplement and the other risk factors described in this section, among other factors, may cause the market price of our common stock to change. In addition, the stock market in general has experienced extreme volatility that has often been unrelated to the operating performance of a particular company. These broad market fluctuations may adversely affect the market price of our common stock.

Our revenues and operating results may fluctuate in future periods, and we may fail to meet expectations, which may cause the price of our common stock to decline.

Our quarterly operating results are difficult to predict and may fluctuate significantly from period to period. We cannot predict with certainty the timing or level of sales of our products in the future. If our quarterly sales or operating results fall below the expectations of investors or securities analysts, the price of our common stock could decline substantially. Our operating results may fluctuate due to various factors including, among other things, the continual pricing pressure of our extremely competitive industry, cyclical industry conditions and volatile raw materials costs as well as our exposure to the

risk of material environmental, health and safety liabilities as a result of our use of significant amounts of lead and acid in our operations. As a result of these factors, we believe that period-to-period comparisons of our operating results are not a good indication of our future performance.

Upon conversion of the notes, we currently intend to pay only cash in settlement of the accreted principal amount or (if lower) the conversion value thereof, and we will settle any amounts in excess thereof in shares of our common stock, cash or a combination thereof, at our election.

We currently intend to satisfy our conversion obligation to holders by paying only cash in settlement of the lesser of the accreted principal amount and the conversion value of the notes and by delivering shares of our common stock, cash or a combination thereof in settlement of the portion of the conversion obligation (if any) in excess of the lesser of the accreted principal amount of the notes and the conversion value of the notes. Accordingly, upon conversion of a note, holders may not receive any shares of our common stock. In addition, unless we elect to satisfy our conversion obligation entirely in shares of our common stock, any settlement of a conversion of notes will occur on the third scheduled day immediately following the 25 consecutive VWAP trading day period beginning on the third VWAP trading day after the conversion date (or (i) in the case of notes surrendered for conversion after the 30th scheduled trading day prior to the maturity date, the 27th scheduled trading day prior to the maturity date or (ii) in the case of notes surrendered for conversion during the 15 calendar day period beginning on, and including, the 16th calendar day immediately preceding any optional redemption date we specify, the optional redemption date), and the value of your converted note will be based upon the daily conversion value of our common stock during a 25 VWAP trading day observation period. Accordingly, you may receive less value than you expected because the value of our common stock may decline (or fail to

appreciate as much as you may expect) between the day that you exercise your conversion right and the day on which we settle our conversion obligation.

Although we currently intend to settle conversions as described above, the terms of the notes allow us to settle any conversions by delivering only shares of our common stock based on the applicable conversion rate. If we elect to settle conversions by delivering only shares of our common stock, we will deliver those shares on the third scheduled trading day after the conversion date (or, in the case of conversions within the 15 calendar day period beginning on, and including, the 16th calendar day immediately preceding any optional redemption date specified by us, on the third scheduled trading day after the last scheduled trading day prior to the relevant redemption date). Therefore, even if we elect to settle conversions solely in shares of our common stock, there may be a delay between the time that you elect to convert and the time that we deliver such shares, and you may receive less value than you expected because the value of our common stock may decline (or fail to appreciate as much as you may expect) between the day that you exercise your conversion right and the day on which we settle our conversion obligation.

The conversion rate of the notes may not be adjusted for all dilutive events that may occur.

As described under “Description of the Notes — Conversion Rights — Conversion Rate Adjustments,” we will adjust the conversion rate of the notes for certain events, including, among others:

We will not adjust the conversion rate for other events, such as an issuance of common stock for cash or in connection with an acquisition, that may adversely affect the trading price of the notes or our common stock. If we engage in any of these types of transactions, the value of the common stock into which your notes may be convertible may be diluted. An event that adversely affects the value of the notes, but does not result in an adjustment to the conversion rate may occur.

The increase in the conversion rate applicable to notes that holders convert in connection with a make-whole fundamental change may not adequately compensate you for the lost option time value of your notes as a result of that designated event.

If a make-whole fundamental change (as defined herein) occurs prior to the maturity date of the notes, we will in some cases increase the conversion rate by an additional number of shares of our common stock for a holder that elects to convert its notes in connection with such make-whole fundamental change. The number of such additional shares depends on the date when such make-whole fundamental change becomes effective and the applicable price described in this prospectus supplement. See “Description of the Notes — Conversion Rights — Adjustment to Shares Delivered upon Conversion in Connection with a Make-Whole Fundamental Change.”

Although the increase in the conversion rate is designed to compensate you for the lost option time value of your notes as a result of such designated event, the increase in the conversion rate is only an approximation of the lost value and may not adequately compensate you for the loss. In addition, you will not be entitled to any additional shares if the applicable price is greater than $250.00 per share or less than $29.00 per share (in each case, subject to adjustment).

Our obligation to increase the conversion rate as described above also could be considered a penalty, in which case the

enforceability thereof would be subject to general principles of equity as they relate to economic remedies. In addition, in no event will the conversion rate exceed 34.4827 shares of common stock per $1,000 in original principal amount of notes, subject to adjustments in the same manner as the conversion rate as set forth under “Description of the Notes — Conversion Rate Adjustments.”

We may not have the ability to pay interest on the notes, to purchase the notes upon a fundamental change or to pay any cash payment due upon conversion, and our other indebtedness then outstanding, including our existing U.S. credit facilities and the proposed new credit facilities, contains or may contain limitations on our ability to pay cash upon conversion or repurchase of the notes.

The notes pay cash interest semi-annually at a rate of 3.375% per year, beginning on December 1, 2008 and ending on June 1, 2015. In addition, beginning with the six-month interest period commencing on June 1, 2015, we may have to pay contingent interest to holders of notes if the market price of the notes exceeds certain thresholds. On each of June 1, 2015, June 1, 2018, June 1, 2023, June 1, 2028, and June 1, 2033, or if a fundamental change occurs, holders of the notes may require us to repurchase, for cash, all or a portion of their notes. In addition, if we have made the irrevocable net share settlement election, then upon conversion of the notes we must pay at least the accreted principal portion in cash. However, we may not have sufficient funds to pay the interest, repurchase price or accreted principal portion when due. In addition, our ability to repurchase the notes or to pay cash upon conversion of the notes may be limited by law, by regulatory authority or by the agreements governing our indebtedness then outstanding. Our existing credit facilities limit us under certain circumstances from making cash net share settlement payments, paying cash in lieu of fractional shares upon conversion of the notes and paying contingent interest, and our new credit facilities may contain restrictions that are

similar or more restrictive. If we fail to pay interest on the notes, repurchase the notes or pay the accreted principal portion of the notes due upon conversion when required, we will be in default under the indenture governing the notes. A default under the indenture or a fundamental change itself could also lead to a default under the agreements governing our other indebtedness, including our existing credit facilities and our proposed new credit facilities. If the repayment of the related indebtedness were to be accelerated after any applicable notice or grace periods, we may not have sufficient funds to repay the indebtedness and repurchase the notes or make cash payments upon conversion thereof. See “Description of the Notes — Interest; Accretion,” and “Description of the Notes — Repurchase at the Option of the Holder — Fundamental Change Permits Holders to Require Us to Repurchase Notes.”

You may not be able to convert your notes before March 1, 2015, and the value of the notes could be less than the value of the common stock into which your notes could otherwise be converted.

Prior to March 1, 2015, the notes are convertible only if specified conditions are met. These conditions may not be met. If these conditions for conversion are not met, you will not be able to convert your notes and you may not be able to receive the value of the common stock into which the notes would otherwise be convertible. In addition, for these and other reasons, the trading price of the notes could be substantially less than the conversion value of the notes.

We have made only limited covenants in the indenture for the notes, and these limited covenants may not protect your investment.

The indenture for the notes does not:

Furthermore, the indenture for the notes contains only limited protections in the event of a change in control and similar transactions. We could engage in many types of transactions, such as acquisitions, refinancings or recapitalizations, that could substantially affect our capital structure and the value of the notes and our common stock but may not constitute a designated event that permits holders to require us to repurchase their notes. For these reasons, you should not consider the covenants in the indenture or the repurchase features of the notes as a significant factor in evaluating whether to invest in the notes.

The definition of a fundamental change requiring us to repurchase the notes is limited and, therefore, the market price of the notes may decline if we enter into a

transaction that is not a fundamental change under the indenture.

The term “fundamental change” requiring us to repurchase the notes at your option is limited to specified corporate transactions and may not include other events that might adversely affect our financial condition. In addition, the requirement that we offer to repurchase the notes upon a fundamental change may not protect holders in the event of a highly leveraged transaction, reorganization, merger or similar transaction involving us.

Conversion of the notes will dilute the ownership interest of existing stockholders, including holders who had previously converted their notes.

To the extent we issue any shares of our common stock upon conversion of the notes, the conversion of some or all of the notes will dilute the ownership interests of existing stockholders, including holders who have received shares of our common stock upon prior conversion of the notes. Any sales in the public market of the common stock issuable upon such conversion could adversely affect prevailing market prices of our common stock. In addition, the existence of the notes may encourage short selling by market participants because the conversion of the notes could depress the price of our common stock.

The accounting for the notes will result in our having to recognize interest expense significantly more than the stated interest rate of the notes in our financial statements after the start of our fiscal year beginning on April 1, 2009.

Under the current accounting rules, for the purpose of calculating diluted earnings per share, a net share settled convertible security meeting certain requirements is accounted for in a manner similar to nonconvertible debt, with the stated coupon constituting interest expense and any shares issuable upon conversion of the security being accounted for in a manner similar to the treasury stock method. The effect

of this method is that the shares potentially issuable upon conversion of the securities are not included in the calculation of earnings per share until the conversion price is “in the money,” and the issuer is then assumed to issue the number of shares necessary to settle the conversion.

However, the Financial Accounting Standards Board (“FASB”) recently posted FASB Staff Position (“FSP”) No. APB 14-1 “Accounting for Convertible Debt Instruments That May Be Settled in Cash upon Conversion (Including Partial Cash Settlements)” (previously FSP APB 14-a), which will change the accounting treatment for net share settled convertible securities. Under the final FSP, cash settled convertible securities will be separated into their debt and equity components. The value assigned to the debt component will be the estimated fair value, as of the issuance date, of a similar debt instrument without the conversion feature, and the difference between the proceeds for the convertible debt and the amount reflected as a debt liability will be recorded as additional paid-in capital. As a result, the debt will be recorded at a discount reflecting its below market coupon interest rate. The debt will subsequently be accreted to its par value over its expected life, with the rate of interest that reflects the market rate at issuance being reflected on the income statement. This change in methodology will affect the calculations of net income and earnings per share for many issuers of cash settled convertible securities. The final FSP will contains explicit disclosure requirements and will be effective for financial statements issued for fiscal years beginning after December 15, 2008, and interim periods within those fiscal years. Early application is not permitted.

There is currently no trading market for the notes, and an active trading market for the notes may not develop or, if it develops, may not be maintained.

The notes are new securities for which there is currently no existing trading market. We do not intend to apply for listing of the notes on any securities exchange or for

quotation of the notes on any automated dealer quotation system. Although the underwriters have informed us that they intend to make a market in the notes, they are not obligated to do so, and may discontinue market-making at any time without notice. Accordingly, an active trading market may not develop for the notes and, even if one develops, such market may not be maintained. If an active trading market for the notes does not develop or is not maintained, the market price and liquidity of the notes are likely to be adversely affected and holders may not be able to sell their notes at desired times and prices or at all. If any of the notes are traded after their purchase, they may trade at a discount from their purchase price.

The liquidity of the trading market, if any, and future trading prices of the notes will depend on many factors, including, among other things, the market price of our common stock, prevailing interest rates, our financial condition, results of operations, business, prospects and credit quality relative to our competitors, the market for similar securities and the overall securities market, and may be adversely affected by unfavorable changes in any of these factors, some of which are beyond our control and others of which would not affect debt that is not convertible into capital stock. Historically, the market for convertible debt has been volatile. Market volatility could materially and adversely affect the notes, regardless of our financial condition, results of operations, business, prospects or credit quality.

The notes have a number of features that may adversely affect their value and trading price, including conversion conditions and the lack of financial covenants. Furthermore, even if the conversion conditions are met, since the conversion value of the notes is dependent on the price of our common

stock, volatile or depressed market prices for our common stock are likely to have a similar effect on the trading prices of the notes. We cannot assure you that the price of our common stock in the future will not have an adverse effect on the trading prices of the notes.

An adverse rating of the notes may cause their trading price to fall.

We have sought to have the notes rated by rating agencies. A rating agency may assign a rating to the notes that is lower than expected. Ratings agencies also may lower ratings on the notes in the future. If rating agencies assign a lower-than-expected rating or reduce, or indicate that they may reduce, their ratings in the future, the trading price of the notes could significantly decline.

You should consider the United States federal income tax consequences of owning the notes.

Pursuant to the terms of the indenture governing the notes, we and every holder agree (in the absence of an administrative pronouncement or judicial ruling to the contrary), for United States federal income tax purposes, to treat the notes as debt instruments that are subject to the Treasury regulations governing contingent payment debt instruments, which we refer to as the contingent debt regulations.

The notes will be treated as issued with original issue discount for United States federal income tax purposes, and you will be required to include such tax original issue discount in your income as it accrues. The amount of original issue discount required to be included by you in income for each year generally is expected to be in excess of the payments and accruals on the notes for non-tax purposes (i.e., in excess of the stated semi-annual regular interest payments and accruals and possibly in excess of any contingent interest payments) in that year.

You will recognize gain or loss on the sale, exchange, conversion, redemption or repurchase of a note in an amount equal to the difference between the amount realized, including the fair market value of any shares of our common stock received, and your adjusted tax basis in the note. Any gain recognized by you on the sale, exchange, conversion, redemption or repurchase of a debenture will be treated as ordinary interest income; any

loss will be ordinary loss to the extent of interest previously included in income, and thereafter will be treated as capital loss.

The conversion rate of the notes will be adjusted in certain circumstances. Under the Internal Revenue Code of 1986 and applicable Treasury regulations, adjustments that have the effect of increasing U.S. Holders’ (as defined in “Certain United States Federal Income Tax Considerations”) interest in our assets or earnings and profits (such as a conversion rate adjustment in connection with a payment of dividends to our stockholders) may, in some circumstances, result in a deemed distribution to the U.S. Holders. If a non-U.S. Holder of the notes were deemed to have received a distribution, the non-U.S. Holder may be subject to United States withholding taxes, subject to reduction if the non-U.S. Holder is eligible for protection under an applicable income tax treaty. You should consult your tax advisor with respect to the United States federal income tax consequences and treatment of any conversion rate adjustments.

A discussion of the United States federal income tax consequences of ownership of the notes and our common stock is contained in this prospectus supplement under the heading “Certain United States Federal Income Tax Considerations.”

As a holder of notes, you will not be entitled to any rights with respect to our common stock, but you will be subject to all changes made with respect to our common stock.

If you hold notes, you will not be entitled to any rights with respect to our common stock (including, without limitation, voting rights and rights to receive any dividends or other distributions on our common stock), but you will be subject to all changes affecting our common stock. You will have the rights with respect to our common stock only when we deliver shares of common stock, if any, to you upon conversion of your notes. For example, in the event that an amendment is proposed to our charter or by-laws requiring

stockholder approval and the record date for determining the stockholders of record entitled to vote on the amendment occurs prior to the date you are deemed to have received common stock, if any, upon conversion, you will not be entitled to vote on the amendment, although you will nevertheless be subject to any changes in the powers, preferences or special rights of our common stock. In addition, because of the contingent conversion feature of the notes, you may not be able to convert your notes until March 1, 2015, and you may not receive any shares upon conversion.

We could be influenced by Metalmark whose interests may not be aligned with the interests of our other stockholders.

Metalmark Capital LLC is a private equity firm that makes investment in a broad range of industries (referred to herein as Metalmark). An affiliate of Metalmark also manages MSCP IV, L.P. and MSCP IV 892, L.P., which together owned approximately 17.02% of our outstanding common stock as of May 16, 2008, pursuant to a subadvisory agreement described under “Certain Relationships and Related Transactions — Relationship with Metalmark and Morgan Stanley” in our Proxy Statement on Schedule 14A, which is incorporated by reference herein from our Annual Report on Form 10-K for the fiscal year ended March 31, 2007. If the secondary offering is consummated, these funds would own 11.84% of our outstanding shares of common stock (or 11.32% if the underwriters exercise in full their option to purchase additional shares). Currently, four of our directors, Howard I. Hoffen, Kenneth F. Clifford, Hwan-yoon F. Chung and Michael C. Hoffman, are employees of Metalmark. As a result of these funds holding 17.02% of our outstanding shares of common stock as of May 16, 2008, and the rights of such funds under the Securityholder Agreement, which is described in portions of our Proxy Statement on Schedule 14A, which are incorporated by reference herein from our Annual Report on Form 10-K for the fiscal year ended March 31, 2007, and Metalmark’s rights under the subadvisory agreement, Metalmark may be able to influence all matters requiring

stockholder approval, including the election of our directors, the adoption of amendments to our certificate of incorporation, the approval of mergers and sales of all or substantially all our assets, decisions affecting our capital structure and other significant corporate transactions as well as matters affecting our management and policies. Circumstances could arise under which the interests of Metalmark could be in conflict with the interests of our other stockholders. The influence of Metalmark may also have the effect of deterring hostile takeovers, delaying or preventing changes in control or changes in management or limiting the ability of our stockholders to approve transactions that they may deem to be in their best interests.

We have ceased to be a “controlled company” for purposes of the New York Stock Exchange listing requirements and will no longer be able to opt out of certain corporate governance requirements.

As of July 5, 2007, we were no longer a “controlled company” for purposes of New York Stock Exchange (“NYSE”) corporate governance listing requirements. As such, subject to certain transition period allowances, we are no longer entitled to opt out of several of the NYSE’s corporate governance requirements. Within one year after July 5, 2007, all of the directors who serve on our Nominating and Corporate Governance Committee will have to meet the NYSE’s independence requirements and our Board will have to be composed of a majority of directors that meet the NYSE’s independence requirements. We may incur incremental costs not reflected in our historical financial statements as a result of any such increased listing compliance, including legal fees and other expenses. In addition, we might not be able to comply with these provisions in a timely fashion. Our failure to comply with these additional NYSE corporate governance listing standards may result in delisting, which could disrupt the trading market for our common shares and result in a significant decline in the value of our common shares.

Shares eligible for future issuance or sale may cause our common stock price to decline, which may negatively impact your investment.

Issuances or sales of substantial numbers of additional shares of our common stock, including in connection with future acquisitions, if any, or the perception that such issuances or sales could occur, may cause prevailing market prices for shares of our common stock to decline and may adversely affect our ability to raise additional capital in the financial markets at a time and price favorable to us. As of the date of this prospectus supplement, our certificate of incorporation provides that we have authority to issue up to 135,000,000 shares of our common stock. As of May 16, 2008,

49,434,419 shares of our common stock were issued and outstanding, and there were no shares of our common stock issued and held in treasury. Also as of such date, there were approximately 2,345,000 shares of our common stock reserved for issuance under stock incentive plans or pursuant to individual option grants or stock awards. As of May 16, 2008, the parties to the Securityholders Agreement collectively owned in excess of 27.8% of our shares, and they may elect to sell their shares of our common stock or exercise their stock options in order to sell the stock underlying their options. If the secondary offering is consummated, such parties ownership would be reduced to 21.0% of our shares (or 20.3% of our shares if the underwriters exercise in full their option to purchase additional shares).

We have not paid, and may not pay, dividends and therefore, unless our stock appreciates in value, investors in our stock may not benefit from holding our stock.

We have not issued a cash dividend on our common stock since we became a public company and we presently intend to continue this policy. Furthermore, our existing U.S. credit facilities limit our ability to pay dividends and our new credit facilities may also do so. As

a result, investors in our common stock may not be able to benefit from owning our common stock unless the shares that these investors acquire appreciate in value. See “Price Range of Common Stock and Divided Policy” in this prospectus supplement.

Provisions in the indenture for the notes, our charter documents and Delaware General Corporation Law may deter or prevent a business combination that may be favorable to you.

If a fundamental change occurs prior to the maturity date of the notes, holders of the notes will have the right, at their option, to require us to repurchase all or a portion of their notes. In addition, if a fundamental change occurs prior to the maturity date of the notes, we will in some cases increase the conversion rate by an additional number of shares of our common stock for a holder that elects to convert its notes in connection with such designated event. In addition, the indenture for the notes prohibits us from engaging in certain mergers or acquisitions unless, among other things, the surviving entity assumes our obligations under the notes. These and other provisions could prevent or deter a third party from acquiring us even where the acquisition could be beneficial to you.

Certain provisions in our certificate of incorporation and bylaws, which are described under “Description of Capital Stock” in the accompanying prospectus, may discourage, delay or prevent a merger or acquisition involving us that our stockholders may consider favorable. For example, our certificate of incorporation authorizes our board of directors to issue shares of preferred stock to which special rights may be attached, including voting and dividend rights. With these rights, preferred stockholders could make it more difficult for a third party to acquire us. In addition, our certificate of incorporation provides for a staggered board of directors, whereby directors serve for three-year terms, with approximately one third of the directors coming up for reelection each year. Having a staggered board of directors makes it more

difficult for a third party to obtain control of our board of directors through a proxy contest, which may be a necessary step in an acquisition of us that is not favored by our board of directors.

In addition, certain other provisions of our corporate documents regarding special meetings of stockholders, advance notice requirements for stockholder proposals and director nominations and amendments of the bylaws and prohibiting stockholder action by written consent and cumulative voting, each of which is described under “Description of Capital Stock — Other Provisions of our Certificate of Incorporation and Bylaws” in the accompanying prospectus, may also discourage, delay or prevent a merger or acquisition involving us that our stockholders may consider favorable.

We are also subject to the anti- takeover provisions of Section 203 of the Delaware General Corporation Law. Under these provisions, if anyone becomes an “interested stockholder,” we may not enter into a “business combination” with that person for three years without special approval, which could discourage a third party from making a takeover offer and could delay or prevent a change of control. For purposes of Section 203, an “interested stockholder” means, generally, someone owning 15% or more of our outstanding voting stock or an affiliate of ours that owned 15% or more of our outstanding voting stock during the past three years, subject to certain exceptions as described in Section 203. See “Description of Capital Stock — Section 203 of the Delaware General Corporation Law” in the accompanying prospectus.

We estimate that the net proceeds from this offering, after deducting estimated fees and expenses and the underwriters’ discounts and commissions, will be approximately $145.8 million (approximately $167.7 million if the underwriters exercise their over-allotment option to purchase additional notes in full).

We intend to use the net proceeds of this offering (including any proceeds we

receive if the underwriters exercise their overallotment option) to pay down outstanding indebtedness under our existing senior secured term loan B, under which $351.4 million in principal amount was outstanding as of May 16, 2008, and which bears interest at a floating rate and matures on March 17, 2011. As of May 16, 2008, the interest rate on borrowings under our senior secured term loan B was 4.6% per annum.

The following table sets forth our unaudited consolidated cash and cash equivalents and our capitalization as of December 31, 2007, on an actual and as adjusted basis for this offering and the application of the net proceeds from this offering (assuming no exercise of the underwriters’ option to purchase additional notes). This offering is not conditioned upon the concurrent offering of our common stock by certain of our stockholders.

You should read the following table in conjunction with management’s discussion and analysis of financial condition and results of operations in our Quarterly Report on Form 10-Q for the quarterly period ended December 30, 2007, which is incorporated by reference in this prospectus supplement.

Our common stock has been listed on the New York Stock Exchange under the symbol “ENS” since it began trading on July 30, 2004. Prior to that time, there had been no public market for our common stock. The following table sets forth, on a per share

basis for the periods presented, the range of high, low and closing prices of our common stock. On May 21, 2008, the last reported sale price for our common stock was $30.19 per share.

We have not issued a cash dividend on our common stock since we became a public company and we presently intend to continue this policy. Furthermore, our existing credit facilities (and our new credit facility may) limit

our ability to pay dividends. We currently intend to retain any earnings for future growth and, therefore, do not expect to pay any cash dividends in the foreseeable future.

We will issue the notes under a base indenture to be dated on or about the closing of this offering, between us and The Bank of New York, as trustee (the “trustee”), as supplemented by a supplemental indenture with respect to the notes. In this section, we refer to the base indenture, as supplemented by the supplemental indenture, as the “indenture.” The terms of the notes include those expressly set forth in the indenture and the notes and those made part of the indenture by reference to the Trust Indenture Act of 1939, as amended (the “Trust Indenture Act”).

The following description is a summary of the material provisions of the notes and the indenture and does not purport to be complete. This summary is subject to and is qualified by reference to all the provisions of the notes and the indenture, including the definitions of certain terms used in the indenture. Wherever particular provisions or defined terms of the indenture or form of note are referred to, these provisions or defined terms are incorporated in this prospectus supplement by reference. You may request a copy of the indenture from us as set forth under the heading “Where You Can Find More Information” in the accompanying prospectus. We urge you to read the indenture (including the form of note contained therein) because it, and not this description, defines your rights as a holder of the notes. The following description supplements, and supersedes to the extent it is inconsistent with, the statements under “Description of Debt Securities” in the accompanying prospectus. For purposes of this description, references to the “Company,” “we,” “our” and “us” refer only to EnerSys and not to its subsidiaries.

General

The notes:

The notes will be our general senior unsecured obligations, ranking equal in right of payment with all of our existing and future senior indebtedness, senior in right of payment to all of our existing and future subordinated indebtedness, effectively subordinate in right of payment to all of the existing and future indebtedness and other liabilities of our subsidiaries and the preferred stock of our subsidiaries to the extent of its liquidation preference and effectively subordinate to any of our existing and future secured indebtedness to the extent of the value of the collateral that secures it. As of December 30, 2007, we had $431.9 million aggregate principal amount of senior indebtedness outstanding, of which $384.1 million was secured.

A significant portion of our operations are conducted through, and most of our assets

are held by, our subsidiaries. As a result, we are dependent on the cash flow of our subsidiaries to meet our debt obligations. Our subsidiaries are separate and distinct legal entities and none of our subsidiaries will guarantee our obligations under, or have any obligation to pay any amounts due on, the notes. As a result, the notes will be effectively subordinated to all liabilities of our subsidiaries, including trade payables, and to any outstanding preferred stock of our subsidiaries, to the extent of its liquidation preference. Our rights and the rights of our creditors, including holders of the notes, to participate in the assets of any of our subsidiaries upon their liquidation or recapitalization will generally be subject to the existing and future claims of those subsidiaries’ creditors and preferred stockholders. In addition, our subsidiaries are not prohibited from incurring additional debt or other liabilities. If our subsidiaries were to incur additional debt or liabilities, our ability to pay our obligations on the notes, including cash payments upon redemption or repurchase, could be adversely affected. As of December 30, 2007, our subsidiaries had $431.9 million aggregate principal amount of indebtedness outstanding and approximately $603.9 million of other liabilities outstanding (excluding intercompany liabilities and liabilities of the type not required to be recorded on the balance sheet in accordance with GAAP).

Subject to the satisfaction of certain conditions and during the periods described below, the notes may be converted into a combination of cash and shares of our common stock (or entirely cash or entirely shares of our common stock, if we so elect) at an initial conversion rate of 24.6305 shares of common stock per $1,000 in original principal amount of notes (equivalent to an initial conversion price of approximately $40.60 per share of common stock). The conversion rate is subject to adjustment if certain events described below occur. However, the conversion rate will not be adjusted for accrued interest or accreted principal in excess of the original $1,000 principal amount. We will settle conversions by delivering a combination of cash and shares of our common stock (or entirely cash or entirely common stock, at our

election), as described under “— Conversion Rights — Settlement upon Conversion.” In addition, at any time on or prior to the 30th “scheduled trading day” (as defined below) prior to the maturity date of the notes, we may irrevocably make the “net share settlement election” (as defined below). See “— Conversion Rights — Settlement upon Conversion.” You will not receive any separate cash payment for interest accrued and unpaid to the “conversion date” (as defined below), except under the limited circumstances described below.

We use the term “note” in this prospectus supplement to refer to each $1,000 in original principal amount of notes.

We may, without the consent of the holders, issue additional notes in an unlimited aggregate original principal amount under the indenture with the same terms and with the same CUSIP numbers as the notes offered hereby; provided that such additional notes are fungible with the notes offered hereby for U.S. federal income tax purposes. We may also from time to time repurchase the notes in open market purchases or negotiated transactions without prior notice to holders.

The registered holder of a note will be treated as the owner of it for all purposes.

Other than the restrictions described under “— Repurchase at the Option of the Holder — Fundamental Change Permits Holders to Require Us to Repurchase Notes” and “— Consolidation, Merger and Sale of Assets” below, and except for the provisions set forth under “— Conversion Rights — Adjustment to Shares Delivered upon Conversion in Connection with a Fundamental Change,” the indenture does not contain any covenants or other provisions designed to afford holders of the notes protection in the event of a highly leveraged transaction involving us or in the event of a decline in our credit rating as the result of a takeover, recapitalization, highly leveraged transaction or similar restructuring involving us that could adversely affect such holders. See “Risk Factors — Risks Related to the Notes.”

No sinking fund is provided for the notes, which means that the indenture does not require us to redeem or retire the notes periodically.

We may be required under certain circumstances to repurchase the notes for cash at a price equal to 100% of the accreted principal amount thereof, plus accrued and unpaid interest, if any, at your request, as described below under “— Repurchase at the Option of the Holder.” Our current and future debt or other agreements may restrict our ability to pay cash upon conversion (if we have not elected to settle our conversion obligation entirely in shares of our common stock) or in connection with a repurchase of notes. Our failure to pay cash upon conversions of the notes or to repurchase the notes, in each case when required, would result in an event of default with respect to the notes. See “Risk Factors — Risks Related to the Offering — We may not have the ability to pay interest on the notes, to purchase the notes upon a fundamental change or to pay any cash payment due upon conversion, and our other indebtedness then outstanding, including our existing U.S. credit facilities and the proposed new credit facilities, contains or may contain limitations on our ability to pay cash upon conversion or repurchase of the notes.”

Payments on the Notes; Paying Agent and Registrar

Through our paying agent, we will pay the principal of, and interest on, notes in global form registered in the name of or held by The Depository Trust Company (“DTC”) or its nominee in immediately available funds to DTC or its nominee, as the case may be, as the registered holder of such global notes.

We will pay the principal of certificated notes at the office or agency designated by us. We have initially designated a corporate trust office of the trustee as our paying agent and registrar as a place where notes may be presented for payment or for registration of transfer. We may, however, change the paying agent or registrar without prior notice to the

holders of the notes, and we may act as paying agent or registrar. Interest on certificated notes will be payable (i) to holders having an aggregate original principal amount of $5.0 million or less, by check mailed to the holders of such notes and (ii) to holders having an aggregate original principal amount of more than $5.0 million, either by check mailed to each holder or, upon application by a holder to the registrar not later than the relevant record date, by wire transfer in immediately available funds to that holder’s account within the United States, which application shall remain in effect until the holder notifies, in writing, the registrar to the contrary.

Transfer and Exchange

A holder of notes may transfer or exchange notes at the office of the registrar in accordance with the indenture. The registrar and the trustee may require a holder, among other things, to furnish appropriate endorsements and transfer documents. No service charge will be imposed by us, the trustee or the registrar for any registration of transfer or exchange of notes, but we, the trustee or registrar may require a holder to pay a sum sufficient to cover any transfer tax or

other similar governmental charge required by law or permitted by the indenture. We are not required to transfer or exchange any note selected or surrendered for conversion.

Interest; Accretion

The notes will bear interest at a rate of 3.375% per year from the date of original issuance, expected to be May 28, 2008, or from the most recent date to which interest has been paid or duly provided for. Interest will be payable semiannually in arrears on June 1 and December 1 of each year, beginning on December 1, 2008 and ending on June 1, 2015. We will not pay cash interest on the notes after June 1, 2015 (except any contingent interest). Commencing on June 1, 2015, the principal amount of the notes will accrete at a rate that provides holders with an aggregate annual yield to maturity of 3.375% per year (computed on a semi-annual bond-equivalent basis). When we refer in this “Description of the Notes” to the “accreted principal amount” of the notes, we mean the original principal amount at any time prior to June 1, 2015, and the principal amount as adjusted upwards for accretion at any time on or after June 1, 2015.

The accreted principal amount of a note between the dates listed above will include an amount reflecting the additional principal accretion that has accrued as of such date since the immediately preceding date in the table.

Interest will be paid to the person in whose name a note is registered at the close of business on May 15 or November 15, as the

case may be, immediately preceding the relevant interest payment date. Interest on the notes will be computed on the basis of a 360-day year composed of twelve 30-day months.

Unless otherwise stated, references to interest in this “Description of the Notes” include contingent interest (as described below under “— Contingent Interest”), if any.

Beginning with the six-month interest period commencing on June 1, 2015, we will pay contingent interest during any six-month interest period to the holders of the notes if the

“trading price” (as defined below) of the notes for each of the five trading days ending on, and including, the second trading day immediately preceding the first day of the applicable

six-month interest period equals or exceeds 130% of the accreted principal amount of the notes.

During any six-month period when contingent interest shall be payable with respect to the notes, the contingent interest payable per $1,000 original principal amount of the notes will equal 0.40% of the average trading price of $1,000 original principal amount of the notes, during the five trading days ending on, and including, the second trading day immediately preceding the first day of the applicable six-month interest period.

“Trading price” for purposes of determining average note value with respect to the notes shall have the meaning set forth under “— Conversion Rights — Conversion upon Satisfaction of Trading Price Condition,” except that, for purposes of determining the trading price for the contingent interest provisions only, if two bids cannot reasonably be obtained for $2.0 million original principal amount of the notes from nationally recognized securities dealers that we have selected, but one such bid can reasonably be obtained, this one bid shall be used. If at least one bid cannot reasonably be obtained for $2.0 million original principal amount of the notes from a nationally recognized securities dealer or in our

reasonable judgment the bid quotations are not indicative of the secondary market value of the notes, then the trading price of the notes will be deemed to equal the product of:

We will notify holders upon a determination that they will be entitled to receive contingent interest during a six-month interest period.

The indenture provides that by accepting a note, each holder agrees, for U.S. federal income tax purposes, to treat the notes as “contingent payment debt instruments” and to be bound by our application of the Treasury regulations that govern contingent payment debt instruments, including our determination that the rate at which interest will be deemed to accrue for U.S. federal income tax purposes will be 8.50%, compounded semi-annually, which is the rate we would pay on a fixed-rate, noncontingent, nonconvertible debt instrument with terms and conditions otherwise comparable to the notes. See “Certain U.S. Federal Income Tax Considerations.”

General

Upon the occurrence of any of the conditions described under the headings “—Conversion upon Satisfaction of Trading Price Condition,” “— Conversion Based on Common Stock Price” and “— Conversion upon Specified Corporate Events,” holders may convert their notes, in whole or in part, at an initial conversion rate of 24.6305 shares of common stock per $1,000 in original principal amount of notes, which is equivalent to an initial conversion price of approximately $40.60 per share of common stock, at any time prior to the close of business on the “scheduled trading day” (as defined below) immediately preceding March 1, 2015. On and after March 1, 2015, holders may convert their

notes at any time prior to the close of business on the scheduled trading day immediately preceding the maturity date of the notes, regardless of the conditions described under the headings “— Conversion upon Satisfaction of Trading Price Condition,” “— Conversion Based on Common Stock Price” and “— Conversion upon Specified Corporate Events.”

“Scheduled trading day” means a day that is scheduled to be a trading day (as defined below) on the principal U.S. national or regional securities exchange or market on which our common stock is listed or admitted for trading or, if our common stock is not listed or admitted for trading on any exchange or market, a business day.

“Trading day” means a day during which (i) trading in our common stock generally occurs and (ii) there is no “market disruption event” (as defined below).

“Market disruption event” means the occurrence or existence on any scheduled trading day for our common stock of any suspension or limitation imposed on trading (by reason of movements in price exceeding limits permitted by the stock exchange or otherwise) in our common stock or in any options contracts or futures contracts relating to our common stock, and such suspension or limitation occurs or exists at any time within the 30 minutes prior to the closing time of the relevant exchange on such day.

The conversion rate and the equivalent conversion price in effect at any given time are referred to as the “applicable conversion rate” and the “applicable conversion price,” respectively, and will be subject to adjustment as described below. The applicable conversion price at any given time will be computed by dividing $1,000 by the applicable conversion rate at such time. A holder may convert fewer than all of such holder’s notes so long as the notes converted are an integral multiple of $1,000 in original principal amount.

Upon conversion, you will not receive any separate cash payment for accrued and unpaid interest unless such conversion occurs between a regular record date and the interest payment date to which it relates. Our settlement of conversions as described below under “— Settlement upon Conversion” will be deemed to satisfy our obligation to pay:

As a result, accrued and unpaid interest to, but not including, the conversion

date will be deemed to be paid in full rather than cancelled, extinguished or forfeited.

Notwithstanding the preceding paragraph, if notes are converted after the close of business on a record date, holders of such notes at the close of business on the record date will receive the interest payable on such notes on the corresponding interest payment date notwithstanding the conversion. Notes surrendered for conversion during the period from and after the close of business on any regular record date to 9:00 a.m., New York City time, on the immediately following interest payment date must be accompanied by funds equal to the amount of interest payable on the notes so converted, except that no such payment need be made:

Upon conversion, we will deliver a combination of cash and shares of our common stock (or entirely cash or entirely shares of our common stock, if we so elect), as described under “— Settlement upon Conversion” below.

If a holder converts notes, we will pay any documentary, stamp or similar issue or transfer tax due on the issue of any shares of our common stock upon the conversion, unless the tax is due because the holder requests any shares to be issued in a name other than the holder’s name, in which case the holder will pay that tax.

Conversion upon Satisfaction of Trading Price Condition

Prior to March 1, 2015, a holder may surrender notes for conversion during the five business day period after any five consecutive trading day period (the “measurement period”) in which the “trading price” (as defined below) per $1,000 in original principal amount of the notes for each day of the measurement period was less than 98% of the product of the “last reported sale price” (as defined below) of our common stock and the applicable conversion rate for the notes for such date, as determined by us and subject to compliance with the procedures and conditions described below concerning the trustee’s obligation to make such determination (the “trading price condition”).

We will have no obligation to determine the trading price of the notes unless a holder provides us with reasonable evidence that the trading price per $1,000 in original principal amount of the notes would be less than 98% of the product of the last reported sale price of our common stock and the applicable conversion rate. At such time, we will determine the trading price of the notes in the manner described below beginning on the next trading day and on each successive trading day until the trading price per $1,000 in original principal amount of the notes is greater than or equal to 98% of the product of the last reported sale price of our common stock and the applicable conversion rate. If we do not, when we are obligated to, determine the trading price of the notes, then the trading price per $1,000 in original principal amount of the notes will be deemed to be less than 98% of the product of the last reported sale price of our common stock and the applicable conversion rate.

If the trading price condition has been met, we will so notify the holders of the notes. If, at any time after the trading price condition has been met, the trading price per $1,000 in original principal amount of the notes is greater than or equal to 98% of the product of the last reported sale price of our common stock and the applicable conversion rate for such date, we will so notify the holders of the notes.

The “trading price” of the notes on any date of determination means the average of the secondary market bid quotations obtained by us or our agent for $2.0 million in original principal amount of the notes at approximately 3:30 p.m., New York City time, on such determination date from three independent nationally recognized securities dealers we select, which may include any or all of the initial purchasers; provided that if three such bids cannot reasonably be obtained, but two such bids are obtained, then the average of the two bids will be used, and if only one such bid is obtained, that one bid will be used. If at least one bid for $2.0 million in original principal amount of the notes cannot reasonably be obtained, then the trading price per $1,000 in original principal amount of the notes will be deemed to be less than 98% of the product of the last reported sale price of our common stock and the applicable conversion rate. Any such determination will be conclusive absent manifest error.

The “last reported sale price” of our common stock on any date means the closing sale price per share (or if no closing sale price is reported, the average of the last bid and ask prices or, if more than one in either case, the average of the average last bid and the average last ask prices) on that date as reported in composite transactions for the principal U.S. national or regional securities exchange on which our common stock is traded. If our common stock is not listed for trading on a U.S. national or regional securities exchange on the relevant date, the “last reported sale price” will be the average of the last quoted bid and ask prices for our common stock in the over-the-counter market on the relevant date as reported by Pink Sheets LLC or a similar organization. If our common stock

is not so quoted, the “last reported sale price” will be the average of the mid-point of the last bid and ask prices for our common stock on the relevant date from each of at least three nationally recognized independent investment banking firms, which may include any or all of the initial purchasers, selected by us for this purpose. Any such determination will be conclusive absent manifest error.

Conversion Based on Common Stock Price

Prior to March 1, 2015, a holder may surrender its notes for conversion during any calendar quarter after the calendar quarter ending on June 30, 2008, (and only during such calendar quarter), if the last reported sale price of our common stock for 20 or more trading days in a period of 30 consecutive trading days ending on the last trading day of the immediately preceding calendar quarter exceeds 130% of the applicable conversion price in effect for the notes on the last trading day of the immediately preceding calendar quarter.

Conversion upon Specified Corporate Events

If we elect to:

If an event constituting a “fundamental change” (as defined below) occurs, we will notify holders and the trustee of the occurrence of any such event no later than the effective date of such event. Once we have given such notice, a holder may surrender notes for conversion at any time from the effective date of such event until the later of (i) the fundamental change repurchase date corresponding to such event and (ii) 35 scheduled trading days following the effective date of such event. In addition, if a fundamental change occurs, a holder may be entitled to receive an increase in the conversion rate in the form of “additional shares” (as defined below) upon any conversion as described below under

“— Adjustment to Shares Delivered upon Conversion In Connection with a Make-Whole Fundamental Change.”

You will also have the right to convert your notes if we are a party to a combination, merger, recapitalization, reclassification, binding share exchange or other similar transaction or sale or conveyance of all or substantially all of our property and assets, in each case pursuant to which our common stock would be converted into cash, securities and/or other property, that does not also constitute a fundamental change. In such event, you will have the right to convert your notes at any time beginning 30 scheduled trading days prior to the anticipated effective date of such transaction and ending on the 35th scheduled trading day following the effective date of such transaction. We will use our reasonable best efforts to notify holders and the trustee at least 33 scheduled trading days prior to the anticipated effective date of any such transaction, and in any event will give such notice no later than the actual effective date of any such transaction.

Conversion on or after March 1, 2015

On or after March 1, 2015, a holder may convert any of its notes at any time prior to the close of business on the scheduled trading day immediately preceding the maturity date, regardless of the foregoing conditions.

Conversion Procedures

If you hold a beneficial interest in a global note, to convert you must comply with DTC’s procedures for converting a beneficial interest in a global note and, if required, pay funds equal to interest payable on the next interest payment date to which you are not entitled and, if required, pay all taxes or duties, if any.

If you hold a certificated note, to convert you must:

The date you comply with these requirements is the “conversion date” under the indenture.

If a holder has already delivered a repurchase notice as described under “— Repurchase at the Option of the Holder — Fundamental Change Permits Holders to Require Us to Repurchase Notes” with respect to a note, such holder may not surrender that note for conversion until the holder has withdrawn the repurchase notice in accordance with the indenture.

Settlement upon Conversion

Upon conversion of the notes, unless we have made the irrevocable net share settlement election (as described below), we may elect to settle conversions of the notes (i) entirely in shares of our common stock, (ii) entirely in cash or (iii) in cash for the “principal portion” (as defined below) and the excess, if any, of the conversion value above the principal portion in a combination of cash and shares of our common stock (“combination settlement”). If we do not elect a settlement method, we will settle conversions using combination settlement, with a “cash percentage” (as defined below) deemed to be 0%. If we make any settlement method election, we will inform the converting holders of such election through the trustee no later than the business day immediately following the related conversion date and, if applicable, we may specify in such notice the percentage (the “cash percentage”) of the daily conversion value in excess of the principal portion that we will satisfy in cash. If we do not specify the cash percentage, the cash percentage will be deemed to be 0%.

Unless we have made the irrevocable net share settlement election, at any time prior to the 30th scheduled trading day prior to the maturity date of the notes, we may deliver a notice to the holders of the notes designating the settlement method for all conversions that occur on or after the 30th scheduled trading day prior to maturity (and, if we elect combination settlement, we will specify the cash percentage for all such conversions, which if not specified will be deemed to be 0%). If we do not deliver such a notice, then we will settle all such conversions in cash up to the principal portion and shares of our common stock for the excess, if any, of the conversion value above the principal portion.

We will treat all holders of notes converting on the same trading day in the same manner. However, we will not have any obligation to settle our conversion obligations arising on different trading days in the same manner, except (1) as described in the immediately succeeding paragraph, (2) for all conversions that occur on or after the 30th scheduled trading day prior to maturity of the notes and (3) where we have made the irrevocable net share settlement election. That is, we may choose on one trading day to settle in shares of our common stock only and choose on another trading day to settle in cash or a combination of cash and shares of our common stock.

If we exercise our optional redemption right as described below under “— Optional Redemption by the Company” and we have not elected to settle our conversion obligation entirely in common stock, the consideration we will deliver to all holders that convert within the 15 calendar day period (the “optional redemption conversion period”) beginning on, and including, the 16th calendar day immediately preceding the optional redemption date will be calculated by reference to an observation period beginning on, and including, the optional redemption date we specify in the “optional redemption notice” (as described below). If we have elected to settle our conversion obligation entirely in common stock, for all conversions occurring during the optional

redemption conversion period, we will deliver a number of shares of our common stock, as calculated under clause (1) below, on the third scheduled trading day following the last scheduled trading day prior to the redemption date.

At any time on or prior to the 30th scheduled trading day prior to the maturity date of the notes, we may irrevocably elect (the “irrevocable net share settlement election”) to settle conversions of the notes in the manner described in clause (2) or (3) below. If we make the irrevocable net share settlement election, we will no longer be permitted under the indenture to settle conversions of the notes in the manner described in clause (1) below. Upon making the irrevocable net share settlement election, we will promptly (i) issue a press release and post such information on our website or otherwise publicly disclose this information and (ii) provide written notice to the holders of the notes in a manner contemplated by the indenture, including through the facilities of the DTC, in which such notice we may specify the cash percentage of the daily conversion value in excess of the daily portion of the accreted principal amount that we will satisfy in cash for all future conversions. If we do not specify a cash percentage in such notice, the cash percentage will be deemed to be 0% for all conversions after we make the irrevocable net share settlement election.

The irrevocable net share settlement election is in our sole discretion and does not require the consent of the holders of the notes.

The settlement amount will be computed as follows:

(1) If we elect to settle any conversion entirely in shares of our common stock, we will deliver a number of shares of our common stock to the holder of the notes on the third scheduled trading day after the relevant conversion date (or, in the case of conversions during the option redemption conversion period, on the third scheduled trading day after the last scheduled trading day prior to the relevant redemption date) equal to (i) (A) the aggregate original principal amount of notes to be converted, divided by (B) $1,000, multiplied

by (ii) the conversion rate in effect on the relevant conversion date.

(2) If we elect (or are deemed to elect) combination settlement or have made the irrevocable net share settlement election and, in each case, have not specified the cash percentage as 100%, we will settle each $1,000 in original principal amount of notes being converted by delivering, on the third scheduled trading day immediately following the last day of the related observation period, cash and shares of our common stock, if any, equal to the sum of the “daily settlement amounts” (as defined below) for each of the 25 VWAP trading days during the related observation period; provided that if we are deemed to have elected combination settlement, we will also be deemed to have elected a cash percentage of 0%.

(3) If we elect to settle any conversion entirely in cash, we will settle each $1,000 in original principal amount of notes being converted by delivering, on the third scheduled trading day immediately following the last day of the related observation period, an amount of cash equal to the sum of the daily conversion values for each of the 25 VWAP trading days during the related observation period. It is our current intent and policy to settle any conversion of the notes as if we had elected to make the net share settlement election in the manner set forth in clause (2) above.

The “daily settlement amount” for each of the 25 VWAP trading days during the observation period means:

The “observation period” with respect to any note means:

The “daily conversion value” means, for each of the 25 consecutive VWAP trading days during the observation period, 1/25th of the product of (1) the applicable conversion rate and (2) the “daily VWAP” (as defined below) of our common stock, or the consideration into which our common stock has been converted in connection with certain corporate transactions, on such VWAP trading day. Any determination of the daily conversion value by us will be conclusive absent manifest error. The “daily VWAP” of our common stock means, for each of the 25 consecutive VWAP trading days during the observation period, the per share volume-weighted average price as displayed under the heading “Bloomberg VWAP” on Bloomberg page ENS.N <equity> AQR (or any equivalent successor page) in respect of the period from the scheduled open of trading on the principal trading market for our common stock to the scheduled close of trading on such market on such VWAP trading day (without regard to after-hours trading), or if such volume-weighted average price is unavailable, the market value of one share of our common stock (or one unit of reference property consisting of marketable equity securities) on such VWAP trading day using a volume-weighted method (or, in the case of reference property consisting of cash, the amount of such cash or in the case of reference property other than marketable equity securities or cash, the market value thereof), in each case as determined by a nationally recognized independent investment banking firm retained for this purpose by us.

“VWAP trading day” means a day during which (i) trading in our common stock generally occurs on the principal U.S. national or regional securities exchange or market on which our common stock is listed or admitted for trading and (ii) there is no “VWAP market disruption event” (as defined below). If our common stock is not so listed or traded, then “VWAP trading day” means a business day.

“VWAP market disruption event” means (i) a failure by the principal U.S. national or regional securities exchange or market on which our common stock is listed or admitted to trading to open for trading during its regular trading session or (ii) the occurrence or existence prior

to 1:00 p.m. on any scheduled trading day for our common stock for an aggregate one half-hour period of any suspension or limitation imposed on trading (by reason of movements in price exceeding limits permitted by the stock exchange or otherwise) in our common stock or in any options contracts or futures contracts relating to our common stock.

Notwithstanding the foregoing, we will deliver cash in lieu of any fractional shares of our common stock deliverable upon conversion based on the daily VWAP on (i) the last VWAP trading day of the applicable observation period in the case of conversions settled in cash or a combination of cash and shares of our common stock and (ii) the conversion date (or, if the conversion date is not on a trading day, the next following trading day) for conversions settled entirely in shares of our common stock.

Exchange in lieu of Conversion

When a holder surrenders its notes for conversion, we may, at our election (an “exchange election”), direct the conversion agent to surrender, on or prior to the second business day following the conversion date, such notes to a financial institution designated by us for exchange in lieu of conversion. In order to accept any notes surrendered for conversion, the designated institution must agree to timely deliver, in exchange for such notes, the cash and/or shares of our common stock that would otherwise be due upon conversion as described above under “— Settlement upon Conversion” (the “conversion consideration”). If we make an exchange election, we will, by the close of business on the second business day following the relevant conversion date, notify the holder surrendering its notes for conversion that we have made the exchange election and we will notify the designated financial institution of the method of settlement we have elected with respect to such conversion and the relevant deadline for delivery of the conversion consideration.

Any notes exchanged by the designated institution will remain outstanding. If the designated institution agrees to accept any notes for exchange but does not timely deliver the related conversion consideration, or if such designated financial institution does not accept the notes for exchange, we will deliver the relevant conversion consideration as if we had not made an exchange election.

Our designation of an institution to which the notes may be submitted for exchange does not require the institution to accept any notes.

Conversion Rate Adjustments

The conversion rate will be adjusted as described below, except that we will not make any adjustments to the conversion rate if holders of the notes participate (as a result of holding the notes, and at the same time as common stockholders participate) in any of the transactions described below as if such holders of the notes held a number of shares of our common stock equal to the applicable conversion rate, multiplied by the original principal amount of notes held by such holders divided by $1,000, without having to convert their notes.

Adjustment Events.

(1) If we issue shares of our common stock as a dividend or distribution on shares of our common stock, or if we effect a share split or share combination, the conversion rate will be adjusted based on the following formula:

where,

CR₀ = the conversion rate in effect as of the close of business on the day immediately preceding the ex-date for such dividend or distribution, or the effective date of such share split or combination, as the case may be;

CR’ = the conversion rate in effect immediately after the opening of business on the ex-date for such dividend or distribution, or the effective date of such share split or combination, as the case may be;

OS₀ = the number of shares of our common stock outstanding immediately prior to the ex-date for such dividend or distribution, or the effective date of such share split or combination, as the case may be; and

OS’ = the number of shares of our common stock that would be outstanding immediately after the opening of business on the ex-date for such dividend or distribution immediately after giving effect to such dividend or distribution or immediately after the effective date of such share split or combination, as the case may be.

Any adjustment made pursuant to this clause (1) shall become effective on the date that is immediately after (x) the ex-date for such dividend or other distribution or (y) the date on which such split or combination becomes effective, as applicable. If any dividend or distribution described in this clause (1) is declared but not paid or made, the new conversion rate shall be readjusted to the conversion rate that would be in effect if such dividend or distribution had not been declared.

(2) If we distribute to all or substantially all holders of our common stock any rights or warrants entitling them for a period of not more than 45 days after the date of such distribution to subscribe for or purchase shares of our common stock, at a price per share less than the average of the last reported sale prices of our common stock for the 10 consecutive trading day period immediately preceding the declaration date for such distribution, the conversion rate will be adjusted based on the following formula:

where,

CR₀ = the conversion rate in effect as of the close of business on the day immediately preceding the ex-date for such distribution;

CR’ = the conversion rate in effect immediately after the opening of business on the ex-date for such distribution;

OS₀ = the number of shares of our common stock outstanding immediately prior to the ex-date for such distribution;

X = the total number of shares of our common stock issuable pursuant to such rights or warrants; and

Y = the number of shares of our common stock equal to the aggregate price payable to exercise such rights or warrants divided by the average of the last reported sale prices of our common stock over the 10 consecutive trading day period ending on the trading day immediately preceding the declaration date for the issuance of such rights or warrants.

For purposes of this clause (2), in determining whether any rights or warrants entitle the holder to subscribe for or purchase our common stock at less than the applicable price of our common stock, and in determining the aggregate exercise or conversion price payable for such common stock, there shall be taken into account any consideration received by the Company for such rights or warrants and any amount payable on exercise or conversion thereof, with the value of such consideration, if other than cash, to be determined by our board or directors or a committee thereof. If any right or warrant described in this paragraph (2) is not exercised or converted prior to the expiration of the exercisability or convertibility thereof, the new conversion rate shall be readjusted to the conversion rate that would have been in effect if our right or warrant had not been issued.

(3) If we distribute shares of our capital stock, evidences of our indebtedness or other assets or property of ours to all or substantially all holders of our common stock, excluding:

then the conversion rate will be adjusted based on the following formula:

where,

CR₀ = the conversion rate in effect as of the close of business on the day immediately preceding the ex-date for such distribution;

CR’ = the conversion rate in effect immediately after the opening of business on the ex-date for such distribution;

SP₀ = the average of the last reported sale prices of our common stock over the 10 consecutive trading day period ending on the trading day immediately preceding the ex-date for such distribution; and

FMV = the fair market value as determined by our board of directors or a committee thereof of the shares of capital stock, evidences of indebtedness, assets or property distributed with respect to each outstanding share of our common stock on the ex-date for such distribution.

With respect to an adjustment pursuant to this clause (3) where there has been a payment of a dividend or other distribution on our common stock in shares of capital stock of any class or series, or similar equity interest, of or relating to a subsidiary or other of our business units, which we refer to as a “spin-off,” the conversion rate in effect

immediately before the close of business on the 10th trading day immediately following the effective date of the spin-off will be increased based on the following formula:

where,

CR₀ = the conversion rate in effect immediately before the close of business on the 10th trading day immediately following the effective date of the spin-off;

CR’ = the conversion rate in effect immediately after the close of business on the 10th trading day immediately following the effective date of the spin-off;

FMV₀ = the average of the last reported sale prices of the capital stock or similar equity interest distributed to holders of our common stock applicable to one share of our common stock over the first 10 consecutive trading day period beginning on, and including, the trading day immediately following the effective date of the spin-off; and

MP₀ = the average of the last reported sale prices of our common stock over the first 10 consecutive trading day period beginning on, and including, the trading day immediately following the effective date of the spin-off.

The adjustment to the conversion rate under this clause (3) will occur at the close of business on the 10th trading day from, and including, the effective date of the spin-off; provided that in respect of any conversion within the 10 trading day period beginning on, and including, the trading day immediately following, and including, the effective date of any spin-off, references in this clause (3) with respect to the spin-off to 10 trading days shall be deemed replaced with such lesser number of trading days as have elapsed between the effective date of such spin-off and the conversion date in determining the applicable conversion rate.

If any such dividend or distribution described in this clause (3) is declared but not paid or made, the new conversion rate shall be readjusted to be the conversion rate that would then be in effect if such dividend or distribution had not been declared.

(4) If we pay any cash dividends or distributions to all or substantially all holders of our common stock, the conversion rate will be adjusted based on the following formula:

where,

CR₀ = the conversion rate in effect as of the close of business on the day immediately preceding the ex-date for such dividend or distribution;

CR’ = the conversion rate in effect immediately after the opening of business on the ex-date for such dividend or distribution;

SP₀ = the average of the last reported sale prices of our common stock during the 10 consecutive trading day period ending on, and including, the trading day immediately preceding the ex-date for such dividend or distribution; and

C = the amount in cash per share we distribute to holders of our common stock.

If any such dividend or distribution described in this clause (4) is declared but not paid or made, the new conversion rate shall be readjusted to be the conversion rate that would then be in effect if such dividend or distribution had not been declared.

(5) If we or any of our subsidiaries make a payment in respect of a tender offer or exchange offer for our common stock, to the extent that the cash and value of any other consideration included in the payment per share of our common stock exceeds the average of the last reported sale prices of our common stock over the 10 consecutive trading

day period beginning on, and including, the trading day next succeeding the last date on which tenders or exchanges may be made pursuant to such tender or exchange offer, the conversion rate will be increased based on the following formula:

where,

CR₀ = the conversion rate in effect at the close of business on the last trading day of the 10 consecutive trading day period commencing on, and including, the trading day next succeeding the date such tender offer or exchange offer expires;

CR’ = the conversion rate in effect on the business day following the last trading day of the 10 consecutive trading day period commencing on, and including, the trading day next succeeding the date such tender or exchange offer expires;

AC = the aggregate value of all cash and any other consideration as determined by our board of directors or a committee thereof paid or payable for shares purchased in such tender or exchange offer;

OS₀ = the number of shares of our common stock outstanding immediately prior to the date such tender or exchange offer expires;

OS’ = the number of shares of our common stock outstanding immediately after the date such tender or exchange offer expires (after giving effect to such tender offer or exchange offer); and

SP’ = the average of the last reported sale prices of our common stock over the 10 consecutive trading day period beginning on, and including, the trading day next succeeding the date such tender or exchange offer expires.

The adjustment to the conversion rate under this clause (5) will occur at the close of

business on the 10th trading day from the trading day next succeeding the date such tender or exchange offer expires; provided that in respect of any conversion within 10 trading days immediately following, and including, the expiration date of any tender or exchange offer, references in this clause (5) with respect to 10 consecutive trading days shall be deemed replaced with such lesser number of trading days as have elapsed between the expiration date of such tender or exchange offer and the conversion date in determining the applicable conversion rate.

If the application of any of the foregoing formulas (other than in respect of a share combination) would result in a decrease in the conversion rate, no adjustment to the conversion rate will be made.

Events that Will Not Result in Adjustments. Except as described in this section or in “— Adjustment to Shares Delivered upon Conversion in Connection with a Fundamental Change” below, we will not adjust the conversion rate. Without limiting the foregoing, the applicable conversion rate will not be adjusted:

Adjustments to the applicable conversion rate will be calculated to the nearest 1/10,000th of a share. No adjustment to the conversion rate will be required unless the adjustment would require an increase or decrease of at least 1% of the conversion rate. However, we will carry forward any adjustments that are less than 1% of the conversion rate that we elect not to make and take them into account upon the earliest of (1) any conversion of notes, (2) each anniversary of the date of issuance of the notes, (3) each VWAP trading day during the period beginning on, and including, the 27th scheduled trading day prior to the maturity date, and (4) such time as all adjustments that have not been made prior thereto would have the effect of adjusting the conversion rate by at least 1%.

Treatment of Reference Property. In the event of:

in which holders of our outstanding common stock would be entitled to receive cash, securities or other property for their shares of common stock, you will be entitled thereafter to convert your notes into the same

type of consideration that you would have been entitled to receive if you had held a number of shares of our common stock equal to the applicable conversion rate in effect immediately prior to these events (such consideration, “reference property”), subject to our right to elect to settle conversions, in whole or in part, in shares of common stock (or reference property), cash or a combination of cash and shares of our common stock (or reference property). However, for any conversions settled in cash or using combination settlement, and for any conversions after we make the irrevocable net share settlement election, upon conversion, you will receive cash and reference property, if any, determined as described under “— Settlement upon Conversion.” The amount of reference property you receive upon conversion will be based on the daily conversion values of reference property and the applicable conversion rate, as described above.

For purposes of the foregoing, the type and amount of consideration that a holder of our common stock would have been entitled to in the case of reclassifications, consolidations, mergers, sales or transfers of assets or other transactions that cause our common stock to be converted into the right to receive more than a single type of consideration determined, based in part upon any form of stockholder election, will be deemed to be (i) if holders of the majority of our shares of common stock affirmatively make such an election, the weighted average of the types and amounts of consideration received by the holders of our common stock that affirmatively make such an election or (ii) if the holders of a majority of our common stock do not affirmatively make such an election, the types and amount of consideration actually received by such holders.

Treatment of Rights. We do not currently have a preferred stock rights plan. To the extent that we have a rights plan in effect upon conversion of the notes into common stock, you will receive, in addition to any common stock and in lieu of any adjustment to the conversion rate, the rights under the rights plan, unless prior to any conversion, the rights

have separated from the common stock, in which case the conversion rate will be adjusted at the time of separation as if we distributed to all holders of our common stock, shares of our capital stock, evidences of indebtedness or assets as described in clause (3) under “— Adjustment Events” above, subject to readjustment in the event of the expiration, termination or redemption of such rights.

Voluntary Increases of Conversion Rate. We are permitted, to the extent permitted by law and the rules of the New York Stock Exchange or any other securities exchange on which our common stock is then listed, to increase the conversion rate of the notes by any amount for a period of at least 20 days, if our board of directors determines that such increase would be in our best interest. If we make such determination, it will be conclusive and we will notify the holders of the notes and the trustee of the increased conversion rate and the period during which it will be in effect at least 15 days prior to the date the increased conversion rate takes effect, and otherwise in accordance with law. We may also, but are not required to, increase the conversion rate to avoid or diminish income tax to holders of our common stock or rights to purchase shares of our common stock in connection with a dividend or distribution of shares or rights to acquire shares or similar event.

Tax Effect. A holder of the notes may, in some circumstances be deemed to have received a distribution or dividend subject to U.S. federal income or withholding tax as a result of an adjustment or the non-occurrence of an adjustment to the conversion rate. For instance, if the conversion rate is adjusted upon the distribution of cash dividends to holders of our shares of common stock, holders of the notes may be deemed to receive a distribution or dividend. For a discussion of the U.S. federal income and withholding tax consequences of certain adjustments, or non-occurrence of certain adjustments, to the conversion rate, see “Certain U.S. Federal Income Tax Considerations.”

Adjustment to Shares Delivered upon Conversion in Connection with a Make-Whole Fundamental Change

If you elect to convert your notes in connection with a “fundamental change” (as defined below) described in clauses (1), (2) or (5) of the definition thereof that occurs on or prior to June 6, 2015 (a “make-whole fundamental change”), the conversion rate will be increased by an additional number of shares of common stock (the “additional shares”) as described below. A conversion shall be deemed to be in connection with a make-whole fundamental change if such conversion occurs on or after the effective date of such make-whole fundamental change and prior to the close of business on the business day immediately prior to the related fundamental change repurchase date. We will notify holders and the trustee of the effective date of any make-whole fundamental change, and issue a press release, on the effective date of such transaction. We will settle conversions of notes as described above under “— Settlement upon Conversion.”

The number of additional shares by which the conversion rate will be increased in the event of a make-whole fundamental change will be determined by reference to the table below, based on the earliest of the date on which such make-whole fundamental change is publicly announced, occurs or becomes effective (the “make-whole reference date”) and the price (the “stock price”) paid per share of our common stock in the make-whole fundamental change. If holders of our common stock receive only cash consideration for their shares of common stock (in a single per-share amount, other than with respect to appraisal and similar rights) in connection with a make-whole fundamental change, the stock price will be the cash amount paid per share in such make-whole fundamental change. Otherwise, the stock price will be the average of the last reported sale prices of our common stock over the 10 consecutive trading day period ending on, and including, the trading day preceding the date on which such make-whole fundamental change occurs or becomes effective.

The stock prices set forth in the first column of the table below (i.e., the row headers) will be adjusted as of any date on which the conversion rate of the notes is otherwise adjusted. The adjusted stock prices will equal the stock prices applicable immediately prior to such adjustment, multiplied by a fraction, the numerator of which is the applicable conversion rate immediately prior to the adjustment giving rise to the stock price adjustment and the denominator of which is the applicable conversion rate as so

adjusted. The number of additional shares will be adjusted in the same manner as the conversion rate as set forth under “— Conversion Rate Adjustments.”

The following table sets forth the adjustments to the conversion rate, expressed as a number of additional shares to be received per $1,000 in original principal amount of the notes, in connection with a make-whole fundamental change.

The exact stock prices and make-whole reference dates may not be set forth in the table above, in which case:

Notwithstanding the foregoing, in no event will the conversion rate exceed 34.4827 shares of common stock per $1,000 in original principal amount of notes, subject to adjustments in the same manner as the conversion rate as set forth under “— Conversion Rate Adjustments.”

Our obligation to increase the conversion rate as described above could be considered a penalty, in which case the enforceability thereof would be subject to general principles of equity as they relate to economic remedies.

Optional Redemption by the Company

Beginning on June 6, 2015, we may redeem any or all of the notes in cash at the redemption price, except for the notes that we are required to repurchase as provided under “— Repurchase at the Option of the Holder.” The redemption price will equal 100% of the accreted principal amount of the notes being redeemed, plus accrued and unpaid interest to, but not including, the redemption date, unless such redemption date falls after a regular record date and on or prior to the corresponding interest payment date, in which case we will pay the full amount of accrued and unpaid interest payable on such interest payment date to the holder of record at the close of business on the corresponding regular record date. Any notes redeemed by us will be paid for in cash.

We will give notice (the “optional redemption notice”) of redemption not more than 60 calendar days but not less than 30 calendar days prior to the redemption date to all record holders at their addresses set forth in the register of the registrar. The optional redemption notice will state, among other things that you have a right to convert the notes called for redemption, and the conversion rate then in effect.

If fewer than all of the outstanding notes are to be redeemed, the trustee will select the notes to be redeemed in original principal amounts of $1,000 or multiples of $1,000 by lot, pro rata or by another method the trustee considers reasonable. If a portion of your notes is selected for redemption and you convert a portion of your notes, the converted portion will be deemed to be of the portion selected for redemption. We may not redeem any notes if we have failed to pay any interest due on the notes and such failure to pay is continuing.

Repurchase at the Option of the Holder

Optional Put

You will have the right to require us to repurchase for cash, at the repurchase price

described below, all or part of your notes on June 1, 2015, June 1, 2018, June 1, 2023, June 1, 2028, and June 1, 2033; provided that you have properly delivered and not withdrawn a written repurchase notice with respect to the notes you require us to repurchase. Notes submitted for repurchase must be $1,000 in original principal amount or whole multiples thereof.

The repurchase price will equal 100% of the accreted principal amount of the notes being repurchased, plus accrued and unpaid interest to, but not including, the repurchase date, unless such repurchase date falls after a regular record date and on or prior to the corresponding interest payment date, in which case we will pay the full amount of accrued and unpaid interest payable on such interest payment date to the holder of record at the close of business on the corresponding regular record date. Any notes repurchased by us will be paid for in cash.

We will give notice (the “optional put notice”) at least 20 business days prior to each repurchase date (the “optional put repurchase date”) to all record holders at their addresses shown in the register of the registrar and to beneficial owners as required by applicable law. This optional put notice will state, among other things, the optional put repurchase date and the procedures that you must follow to require us to repurchase your notes.

Fundamental Change Permits Holders to Require Us to Repurchase Notes

If a fundamental change occurs at any time, you will have the right, at your option, to require us to repurchase any or all of your notes, or any portion of the original principal amount thereof that is equal to $1,000 or an integral multiple of $1,000, on a date (the “fundamental change repurchase date”) of our choosing that is not less than 15 nor more than 35 days after the date of the “fundamental change repurchase right notice” (as defined below). The price we are required to pay is equal to 100% of the accreted principal amount of the notes to be repurchased plus accrued and unpaid interest to, but not including, the

fundamental change repurchase date, unless such fundamental change repurchase date falls after a regular record date and on or prior to the corresponding interest payment date, in which case we will pay the full amount of accrued and unpaid interest payable on such interest payment date to the holder of record as of the close of business on the corresponding regular record date. Any notes repurchased by us will be paid for in cash.

A “fundamental change” will be deemed to have occurred if any of the following occurs:

(1) any person acquires beneficial ownership, directly or indirectly, through a purchase, tender or exchange offer, merger or other acquisition, transaction or series of transactions, of shares of our capital stock entitling the person to exercise 50% or more of the total voting power of all shares of our capital stock entitled to vote generally in elections of directors and files a Schedule 13D or Schedule TO or any other schedule, form or report under the Exchange Act disclosing such beneficial ownership or we otherwise know of such beneficial ownership; provided, however, that a fundamental change shall not occur as a result of this clause (1) if clause (2) also applies in which case clause (2) below shall apply; or

(2) we (i) merge or consolidate with or into any other person, another person merges with or into us, or we convey, sell, transfer or lease all or substantially all of our assets to another person or (ii) engage in any recapitalization, reclassification or other transaction in which all or substantially all of our common stock is exchanged for or converted into cash, securities or other property, in each case, other than any merger or consolidation:

(3) the first day on which a majority of the members of our board of directors does not consist of continuing directors; or

(4) we are liquidated or dissolved or holders of our common stock approve any plan or proposal for our liquidation or dissolution; or

(5) if shares of our common stock, or shares of any other common stock into which the notes are convertible pursuant to the terms of the indenture, are not listed for trading on any of the New York Stock Exchange, the NASDAQ Global Market or the NASDAQ Global Select Market (or any of their respective successors);

provided that the definition of fundamental change shall not include a merger or consolidation under clause (1) or any event specified under clause (2), in each case, if at least 90% of the consideration paid for our common stock (excluding cash payments for fractional shares and cash payments made pursuant to dissenters’ appraisal rights and cash dividends) in connection with such event consists of shares of common stock traded on any of the New York Stock Exchange, the NASDAQ Global Market or the NASDAQ Global Select Market (or any of their respective

successors) (or that will be so traded immediately following the completion of the merger or consolidation or such other transaction) and, as a result of such transaction or transactions, the notes become convertible into such shares of such common stock pursuant to “— Conversion Rate Adjustments — Treatment of Reference Property” above.

For purposes of these provisions, whether a person is a “beneficial owner” will be determined in accordance with Rule 13d-3 under the Exchange Act, and “person” includes any syndicate or group that would be deemed to be a “person” under Section 13(d)(3) of the Exchange Act.

The phrase “all or substantially all” as it is used in the definition of fundamental change will likely be interpreted under applicable state law and will be dependent upon particular facts and circumstances. There is a degree of uncertainty in interpreting this phrase. Accordingly, the ability of a holder of the notes to require us to purchase its notes as a result of the sale, lease or transfer of less than all of our assets may be uncertain.

“Continuing directors” means (i) individuals who on the date of original issuance of the notes constituted our board of directors and (ii) any new directors whose election to our board of directors or whose nomination for election by our stockholders was approved by at least a majority of our directors then still in office (or a duly constituted committee thereof), either who were directors on the date of original issuance of the notes or whose election or nomination for election was previously so approved.

After the occurrence of a fundamental change, but on or before the 15th day following such occurrence, we will notify all holders of the notes and the trustee and paying agent on the occurrence of the fundamental change and of the resulting repurchase right, if any (the “fundamental change repurchase right notice”). Such notice shall state, among other things: