SUMMARY

        This summary highlights selected information contained elsewhere in this proxy statement/prospectus and may not contain all the information that may be important to you. Accordingly, we encourage you to read this proxy statement/prospectus carefully and in its entirety, including the Annexes to, and the documents incorporated by reference in, this proxy statement/prospectus, and the registration statement to which this proxy statement/prospectus relates, including the exhibits thereto. The page references have been included in this summary to direct you to a more complete description of the topics presented below. See also the section entitled "Where You Can Find More Information" beginning on page 186.

        References to "Sinclair" are references to Sinclair Broadcast Group, Inc. References to "Tribune" are references to Tribune Media Company. References to "we" or "our" and other first person references in this proxy statement/prospectus refer to both Sinclair and Tribune, before closing of the transaction. References to "Merger Sub" are references to Samson Merger Sub Inc., a wholly-owned subsidiary of Sinclair. References to the "transaction," unless the context requires otherwise, means the transactions contemplated by the merger agreement, taken as a whole.

Parties to the Transaction (Page 55)

Sinclair Broadcast Group, Inc.

        Sinclair Broadcast Group, Inc., a Maryland corporation that was founded in 1986 and became a public corporation in 1995, is a diversified television broadcast company with national reach with a strong focus on providing high-quality content on its local television stations and digital platforms. As of December 31, 2016, Sinclair's broadcast distribution platform was a single reportable segment for accounting purposes, consisting primarily of its broadcast television stations, which Sinclair owns, and provides programming and operating services pursuant to local marketing agreements, which we refer to as "LMAs," and also provides sales services and other non-programming operating services pursuant to other outsourcing agreements (such as joint sales agreements, which we refer to as "JSAs" and shared services agreements, which we refer to as "SSAs") to 173 stations in 81 markets.

        The content, distributed through Sinclair's broadcast platform, consists of programming provided by third-party networks and syndicators, local news, Sinclair's own networks, and other original programming produced by Sinclair. Sinclair also distributes its own original programming, and owned and operated networks, on other third-party platforms. Additionally, Sinclair owns digital and internet media products that are complementary to Sinclair's extensive portfolio of television station related digital properties. Sinclair focuses on offering marketing solutions to advertisers through its television and digital platforms and digital agency services. Outside of Sinclair's media related businesses, Sinclair operates technical services companies focused on supply and maintenance of broadcast transmission systems as well as research and development for the advancement of broadcast technology, and Sinclair manages other non-media related investments. Sinclair Class A common stock is listed on the NASDAQ under the symbol "SBGI." Sinclair's principal executive office is located at 10706 Beaver Dam Road, Hunt Valley, MD 21030 (telephone number: (410) 568-1500).

        This proxy statement/prospectus incorporates important business and financial information about Sinclair from other documents that are not included in or delivered with this proxy statement/prospectus. For a list of the documents that are incorporated by reference, see "Where You Can Find More Information" beginning on page 186 of this proxy statement/prospectus and "Incorporation of Certain Documents by Reference" beginning on page 184 of this proxy statement/prospectus.

Tribune Media Company

        Tribune Media Company, a Delaware corporation, was founded in 1847 as a newspaper publisher and incorporated in Delaware in 1968. Tribune is a diversified media and entertainment business

comprised of 42 television stations, that are either owned by Tribune or others, but to which Tribune provides certain services, along with a national general entertainment cable network, a radio station, a production studio, a portfolio of real estate assets and investments in a variety of media, websites and other related assets.

        Tribune is one of the largest independent station owner groups in the United States based on household reach, and owns or operates local television stations in each of the nation's top five markets and seven of the top ten markets by population. Tribune has network affiliations with all of the major over-the-air networks, including American Broadcasting Company, which we refer to as "ABC," CBS Corporation, which we refer to as "CBS," Fox Broadcasting Company, which we refer to as "FOX," National Broadcasting Company, which we refer to as "NBC," and The CW Network, LLC, which we refer to as the "CW." Tribune provides "must-see" programming, including the National Football League, which we refer to as the "NFL" and other live sports, on many of its stations and local news to approximately 50 million U.S. households in the aggregate, as measured by Nielsen Media Research, representing approximately 44% of all U.S. households. In addition, Tribune owns a national general entertainment cable network, WGN America, which we refer to as "WGNA," which is available in approximately 80 million households nationally, as estimated by Nielsen Media Research. WGNA provides Tribune with a platform for launching original programming and exclusive syndicated content.

        Tribune also holds a variety of investments in cable and digital assets, including equity investments in Television Food Network, G.P., which we refer to as "TVFN," and CareerBuilder, LLC, which we refer to as "CareerBuilder." On June 19, 2017, Tribune announced its expected share of the proceeds as a result of the sale of CareerBuilder, in which Tribune holds a 32.1% ownership interest, to an investor group led by investment funds managed by affiliates of Apollo Global Management and the Ontario Teachers' Pension Plan Board. Tribune expects to retain an approximate 8% ownership stake in CareerBuilder on a fully-diluted basis following the sale. The transaction, which is subject to regulatory approval and customary closing conditions, is expected to close in the third quarter of 2017.

        Tribune Class A common stock is listed on the NYSE under the trading symbol "TRCO." Tribune Class B common stock is quoted on the OTC Pink market under the trading symbol "TRBAB." Tribune's principal executive office is located at 435 North Michigan Avenue, Chicago, Illinois 60611 (telephone number: (212) 210-2786).

        This proxy statement/prospectus incorporates important business and financial information about Tribune from other documents that are not included in or delivered with this proxy statement/prospectus. For a list of the documents that are incorporated by reference, see "Where You Can Find More Information" beginning on page 186 of this proxy statement/prospectus and "Incorporation of Certain Documents by Reference" beginning on page 184 of this proxy statement/prospectus.

Samson Merger Sub Inc.

        Samson Merger Sub Inc., a Delaware corporation and a wholly owned subsidiary of Sinclair, was formed solely for the purpose of consummating the merger of Merger Sub with and into Tribune, as provided for in the merger agreement. Merger Sub has not carried on any activities to date, except for activities incidental to its formation and activities undertaken in connection with the transactions contemplated by the merger agreement.

        Samson Merger Sub Inc.'s office is located at 10706 Beaver Dam Road, Hunt Valley, MD 21030 (telephone number: (410) 568-1500).

The Transaction (see Page 56)

        On May 8, 2017, Sinclair, Tribune and Merger Sub entered into the merger agreement, pursuant to which Merger Sub will merge with and into Tribune, as a result of which Tribune will be acquired by Sinclair.

        In the merger, each share of Tribune Class A common stock and Tribune Class B common stock issued and outstanding immediately prior to the effective time (other than shares held by Tribune or any Tribune subsidiary or Sinclair or any Sinclair subsidiary) will be converted into the right to receive (i) $35.00 in cash, without interest and less any required withholding taxes and (ii) 0.2300 of a share of Sinclair's Class A common stock.

        No fractional shares of Sinclair Class A common stock will be issued in the merger. Tribune shareholders will receive cash, without interest, in lieu of any fractional shares.

        For a description of the treatment of stock options and other equity awards of Tribune, see "The Agreements—Description of the Merger Agreement—Treatment of Stock Options, Warrants and Other Stock-Based Awards" beginning on page 127.

Tribune Board Reasons for the Transaction and Recommendation (Page 66)

        The Tribune board has unanimously (i) determined that the terms of merger agreement and the transactions contemplated by the merger agreement are fair to, and in the best interests of, Tribune and the Tribune shareholders, (ii) determined that it is in the best interests of Tribune and the Tribune shareholders and declared it advisable for Tribune to enter into the merger agreement and perform its obligations thereunder, (iii) approved the execution and delivery by Tribune of the merger agreement, the performance by Tribune of its covenants and agreements contained therein and the consummation of the transactions contemplated by the merger agreement, including the merger, upon the terms and subject to the conditions contained therein, (iv) recommended that the Tribune shareholders approve the merger and adopt the merger agreement and (v) directed that the merger agreement be submitted to the Tribune shareholders at a meeting of the Tribune shareholders for their adoption in accordance with DGCL. Tribune's board unanimously recommends that its shareholders vote "FOR" the merger proposal, "FOR" the compensation proposal and "FOR" the adjournment proposal.

        The Tribune board considered many factors in making its determination that the merger agreement and the transactions contemplated by the merger agreement are fair to, and in the best interests of, Tribune and its shareholders. For a more complete discussion of these factors, see "Transaction Summary—Tribune's Reasons for the Transaction and Recommendation of the Tribune Board" beginning on page 66.

Sinclair Board Reasons for the Transaction (Page 71)

        The board of directors of Sinclair, which we refer to as the "Sinclair board," considered a number of factors in making its determination to approve the transaction. These factors are described in "Transaction Summary—Sinclair's Reasons for the Transaction" beginning on page 71.

Opinions of Tribune's Financial Advisors (Page 73)

Opinion of Moelis & Company (see page 73)

        At the meeting of the Tribune board on May 7, 2017 to evaluate and approve the merger, Moelis & Company, which we refer to as "Moelis," delivered an oral opinion (which was subsequently confirmed by delivery of a written opinion, dated May 7, 2017) addressed to the Tribune board that, based upon and subject to the qualifications, conditions, limitations and assumptions stated in its opinion, as of the date of the opinion, the merger consideration to be received by the Tribune

shareholders, other than Sinclair, Tribune, Merger Sub, Oaktree shareholders, Tribune shareholders who have demanded appraisal for such shares, and the respective affiliates of any of the foregoing, which we refer to collectively as the "Excluded Holders," in the merger is fair, from a financial point of view, to such holders.

        The full text of Moelis's written opinion dated May 7, 2017, which sets forth the assumptions made, procedures followed, matters considered and limitations on the review undertaken in connection with the opinion, is attached as Annex C to this proxy statement/prospectus and is incorporated herein by reference. Moelis's opinion was provided for the use and benefit of Tribune's board (solely in its capacity as such) in its evaluation of the merger. Moelis's opinion is limited solely to the fairness, from a financial point of view, of the merger consideration to be received by the Tribune shareholders, other than the Excluded Holders, and does not address Tribune's underlying business decision to effect the merger or the relative merits of the merger as compared to any alternative business strategies or transactions that might be available with respect to Tribune. Moelis's opinion does not constitute a recommendation to any Tribune shareholders as to how such shareholder should vote or act with respect to the merger or any other matter.

        For a description of the opinion that the Tribune board received from Moelis, see "Transaction Summary—Opinions of Tribune's Financial Advisors—Moelis & Company" beginning on page 73.

Opinion of Guggenheim Securities, LLC (see page 85)

        At the meeting of the Tribune board on May 7, 2017 to evaluate and approve the merger, Guggenheim Securities, LLC, which we refer to as "Guggenheim Securities," delivered an oral opinion (which was subsequently confirmed by delivery of a written opinion, dated May 7, 2017) addressed to the Tribune board that, as of May 7, 2017 and based on and subject to the matters considered, the procedures followed, the assumptions made and various limitations of and qualifications to the review undertaken, the merger consideration was fair, from a financial point of view, to the Tribune shareholders (excluding Sinclair and its affiliates). The full text of Guggenheim Securities' written opinion, which is attached as Annex D to this proxy statement/prospectus and which you should read carefully and in its entirety, is subject to the assumptions, limitations, qualifications and other conditions contained in such opinion and is necessarily based on economic, capital markets and other conditions, and the information made available to Guggenheim Securities, as of the date of such opinion.

        Guggenheim Securities' opinion was provided to the Tribune board (in its capacity as such) for its information and assistance in connection with its evaluation of the merger consideration. Guggenheim Securities' opinion and any materials provided in connection therewith did not constitute a recommendation to the Tribune board with respect to the merger nor does Guggenheim Securities' opinion constitute advice or a recommendation to any Tribune shareholder as to how to vote or act in connection with the merger or otherwise. Guggenheim Securities' opinion addresses only the fairness, from a financial point of view and as of the date of such opinion, of the merger consideration to the Tribune shareholders (excluding Sinclair and its affiliates) to the extent expressly specified in such opinion and does not address any other term, aspect or implication of the merger, the merger agreement (including, without limitation, the form or structure of the merger), any shareholder voting agreement, other agreement, transaction document or instrument contemplated by the merger agreement or to be entered into or amended in connection with the merger or Sinclair's debt commitment letters or any financing or other transactions related thereto.

        For a description of the opinion that the Tribune board received from Guggenheim Securities, see "Transaction Summary—Opinions of Tribune's Financial Advisors—Guggenheim Securities, LLC" beginning on page 85.

Key Terms of the Merger Agreement (Page 126)

Conditions to the Closing of the Transaction (See Page 149)

        The merger agreement contains customary closing conditions, including the following conditions that apply to the obligations of both Tribune and Sinclair to consummate the transactions:

•

Tribune shareholders' approval of the merger;



•

receipt of certain regulatory approvals, including approval from the FCC, the expiration or termination of the waiting period applicable to the merger under the HSR Act, and the approval for listing by the NASDAQ of the Sinclair Class A common stock to be issued in the merger; and



•

the absence of certain legal impediments to the consummation of the merger.

        In addition to the foregoing conditions, Sinclair's and Merger Sub's obligations to consummate the merger are subject to the satisfaction or waiver of the following conditions:

•

the accuracy of the representations and warranties of Tribune (with certain exceptions for inaccuracies that are de minimis, that are not material or that have not had and would not reasonably be expected to have, individually or in the aggregate, a material adverse effect on Tribune and its subsidiaries, taken as a whole);



•

the performance in all material respects of Tribune with its covenants and agreements in the merger agreement; and



•

since May 8, 2017, there not having been any effect, change, condition, fact, development, occurrence or event that, individually or in the aggregate has had or would be reasonably likely to have a material adverse effect on Tribune and its subsidiaries, taken as a whole.

        In addition to the foregoing conditions, Tribune's obligations to consummate the Merger are subject to the satisfaction or waiver of the following conditions:

•

the accuracy of the representations and warranties of Sinclair and Merger Sub (with certain exceptions for inaccuracies that are de minimis, that are not material or that have not had and would not reasonably be expected to have, individually or in the aggregate, a material adverse effect on Sinclair and its subsidiaries, taken as a whole);



•

the performance in all material respects of Sinclair with its covenants and agreements in the merger agreement; and



•

since May 8, 2017, there has not been any material adverse effect on Sinclair and its subsidiaries, taken as a whole.

No Solicitation (See Page 140)

        As more fully described in this proxy statement/prospectus and as set forth in the merger agreement, Tribune has agreed, among other things, not to:

•

solicit, initiate or knowingly encourage or knowingly facilitate any inquiry, proposal or offer which constitutes, or would reasonably be expected to lead to, an alternative acquisition proposal; and



•

subject to certain exceptions, participate in any discussions or negotiations regarding, or furnish to any other person any nonpublic information relating to Tribune and its subsidiaries, in connection with any an alternative acquisition proposal.

        Prior to the time that Tribune receives shareholder approval of the merger proposal:

•

the Tribune board may, upon receipt of a bona fide written alternative acquisition proposal, determine in good faith, after consultation with Tribune's outside financial advisors and outside legal counsel, that such acquisition proposal constitutes a superior proposal or would reasonably be expected to lead to a superior proposal and that the failure to take certain actions would be reasonably expected to be inconsistent with the Tribune board's fiduciary duties to Tribune shareholders under applicable law, then Tribune may furnish information with respect to Tribune and its subsidiaries to the person making the proposal and engage in discussions or negotiations with such person and their representatives regarding such proposal, subject to the terms of the merger agreement; and



•

Tribune may, subject to compliance with certain obligations set forth in the merger agreement, including the payment of a termination fee to Sinclair, terminate the merger agreement to enter into a definitive agreement to accept a bona fide written alternative acquisition proposal that constitutes a superior proposal in accordance with the merger agreement, subject to certain notice and matching rights in favor of Sinclair.

        For additional detail of the these provisions, see "The Agreements—Description of the Merger Agreement—Restrictions on Tribune's Solicitation of Acquisition Proposals" beginning on page 137 and "The Agreements—Description of the Merger Agreement—Change of Recommendation by the Tribune Board" beginning on page 139.

Termination of the Merger Agreement (See Page 148)

        The merger agreement may be terminated at any time prior to the effective time:

•

by mutual written consent of Sinclair and Tribune;



•

by either Sinclair or Tribune:



•

if the effective time has not occurred on or before May 8, 2018, subject to an automatic extension to August 8, 2018 in certain circumstances, if the only outstanding unfulfilled conditions relate to HSR approval or FCC approval, which we refer to as the "end date." Notwithstanding the foregoing, the right to terminate the merger agreement under this clause will not be available to a party if the failure of the effective time to occur before the end date was primarily due to such party's breach of any of its obligations under the merger agreement;



•

if any governmental authority of competent jurisdiction has issued a final and non-appealable order permanently prohibiting the consummation of the merger; provided that the Party seeking to terminate the merger agreement under this clause will have used its reasonable best efforts to have such order lifted; or



•

if, after completion of the special meeting (including any adjournment or postponement thereof), the Tribune shareholders have not approved the merger proposal;



•

by Sinclair:



•

at any time prior to the special meeting, if Tribune has materially breached any of its obligations with respect to the Tribune special meeting or its no solicitation obligations;



•

if the Tribune board or any committee thereof (i) withdraws, amends, changes, modifies or qualifies, or otherwise proposes publicly to withdraw, amend, change, modify or qualify, in a manner adverse to Sinclair, its recommendation that the Tribune shareholders approve the merger and adopt the merger agreement, (ii) fails to make such recommendation in the proxy statement; (iii) approves or recommends, or otherwise proposes publicly to approve or

recommend, an alternative acquisition proposal or (iv) fails to publicly recommend against an alternative acquisition proposal that has been publicly disclosed within 10 business days of Sinclair's request and fails to reaffirm its recommendation within such period upon such request (provided that such a request may be delivered by Sinclair only once with respect to each alternative acquisition proposal, with the right to make an additional request with respect to each subsequent material amendment or modification thereto);

•

if Tribune or any of its subsidiaries shall have entered into any agreement, other than a confidentiality agreement that contains provisions that in the aggregate are no less favorable to Tribune than those contained in the confidentiality agreement executed by Sinclair (provided that any such agreement need not contain any "standstill" or similar provisions) and that does not contain any provision that would prevent Tribune from complying with its obligation to provide any disclosure to Sinclair required pursuant to the merger agreement, which we refer to as an "acceptable confidentiality agreement," with respect to an alternative acquisition proposal; or



•

if the closing conditions relating to the accuracy of Tribune's representations and warranties or fulfillment of Tribune's covenants cannot be satisfied due to a breach by Tribune of its representations and warranties or failure to perform any of its covenants contained in the merger agreement that would give rise for a failure of the applicable condition in the merger agreement to be satisfied, which breach is incapable of being cured by Tribune within 30 days of written notice of such breach from Sinclair, or if capable of being cured within such period, is not cured by the earlier of such period and the end date; provided that if such breach or failure to perform is capable of being cured by Tribune and Tribune ceases using reasonable best efforts to cure such breach or failure to perform following written notice from Sinclair, Sinclair will have the right to terminate the merger agreement; provided, further, that Sinclair will not have the right to terminate the merger agreement if Sinclair or Merger Sub is then in breach of any of its representations, warranties, covenants or agreements such that Tribune has the right to terminate the merger agreement;



•

by Tribune:



•

if the closing conditions relating to the accuracy of Sinclair's or Merger Sub's representations and warranties or fulfillment of Sinclair's or Merger Sub's covenants cannot be satisfied due to a breach by Sinclair of its representations and warranties or failure to perform any of its covenants contained in the merger agreement that would give rise for a failure of the applicable condition in the merger agreement to be satisfied, which breach is incapable of being cured by Sinclair within 30 days of written notice of such breach from Tribune, or if capable of being cured within such period, is not cured by the earlier of such period and the end date; provided that if such breach or failure to perform is capable of being cured by Sinclair and Sinclair ceases using reasonable best efforts to cure such breach or failure to perform following written notice from Tribune, Tribune will have the right to terminate the merger agreement; provided, further, that Tribune will not have the right to terminate the merger agreement if Tribune is then in breach of any of its representations, warranties, covenants or agreements such that Tribune has the right to terminate the merger agreement; or



•

if the Tribune board authorizes Tribune to enter into an alternative acquisition agreement with respect to a superior proposal further described in "The Agreements—Description of the Merger Agreement—Change of Recommendation by the Tribune Board" beginning on page 139, substantially concurrently with the termination of the merger agreement, and Tribune pays the termination fee described in "The Agreements—Description of the Merger Agreement—Termination Fee" beginning on page 150.

Termination Fee (See Page 150)

        Tribune must pay Sinclair a termination fee of $135.5 million if:

•

Sinclair terminates the merger agreement due to Tribune having materially breached any of its obligations with respect to the special meeting or its no solicitation obligations;



•

Sinclair terminates the merger agreement due to (a) the Tribune board or any committee thereof (i) withdrawing, amending, changing, modifying or qualifying, or otherwise proposing publicly to take any of the foregoing actions in a manner adverse to Sinclair, its recommendation that the Tribune shareholders approve the merger and adopt the merger agreement, (ii) failing to make such recommendation in the proxy statement; (iii) approving or recommending, or otherwise proposing publicly to approve or recommend, an alternative acquisition proposal or (iv) failing to publicly recommend against an alternative acquisition proposal that has been publicly disclosed within 10 business days of Sinclair's request and failing to reaffirm its recommendation within such period upon such request (provided that such a request may be delivered by Sinclair only once with respect to each alternative acquisition proposal, with the right to make an additional request with respect to each subsequent material amendment or modification thereto) or (b) Tribune or any of its subsidiaries having entered into any agreement, other than an acceptable confidentiality agreement, with respect to an alternative acquisition proposal; or



•

Tribune terminates the merger agreement due to the Tribune board authorizing Tribune to enter into an alternative acquisition agreement with respect to a superior proposal further described in "The Agreements—Description of the Merger Agreement—Change of Recommendation by the Tribune Board" beginning on page 139, and Tribune pays the termination fee at or prior to the termination of the merger agreement as further described in "The Agreements—Description of the Merger Agreement—Termination Fee" beginning on page 150.

        Tribune must pay Sinclair a termination fee of $135.5 million (except that the termination fee of $135.5 million will be reduced by any previously paid amount of the termination fee of $38.5 million plus the documented, out of pocket expenses of Sinclair in an amount not to exceed $10 million as described below) if:

•

Sinclair or Tribune terminates the merger agreement if the effective time has not occurred prior to the end date of May 8, 2018, subject to an automatic extension to August 8, 2018 in certain circumstances, if the only outstanding unfulfilled conditions relate to HSR approval or FCC approval as described in "The Agreement—Description of the Merger Agreement—Termination" or the Tribune shareholders do not approve the transaction; or



•

Sinclair terminates the merger agreement in respect of a willful breach of Tribune's covenants or agreements that would give rise to the failure of a closing condition that is incapable of being cured within 30 days after Tribune receives written notice from Sinclair of such breach, or if capable of being cured in such 30 days period, is not so cured during the earlier of such 30 day period and the end date; and,

in the case of the foregoing clauses, an alternative acquisition proposal has been made to Tribune and publicly announced and not withdrawn prior to the termination or the date of the special meeting, as applicable, and within twelve months after termination of the merger agreement, Tribune enters into a definitive agreement with respect to an alternative acquisition proposal (and subsequently consummates such transaction) or consummates a transaction with respect to an alternative acquisition proposal. For purposes of this termination fee, references to "85%" and "15%" will be replaced by "50%" in the definition of "alternative acquisition proposal" in the merger agreement.

        Tribune must pay Sinclair a termination fee of $38.5 million plus the documented, out-of-pocket costs and expenses of Sinclair in an amount not to exceed $10 million if Sinclair or Tribune terminates the merger agreement because the Tribune shareholders do not approve the transaction.

        If paid, the $38.5 million termination fee, plus the amount of Sinclair's expenses not to exceed $10 million would be credited against any $135.5 million termination fee that Tribune subsequently is required to pay Sinclair.

Expenses (See Page 151)

        Other than as described in "The Agreements—Description of the Merger Agreement—Termination" beginning on page 148, whether or not the transaction is consummated, all costs and expenses incurred in connection with the merger agreement will be borne by the party incurring such expenses, except that Sinclair and Tribune will each be responsible for 50% of the filing fees related to filings with the FCC and under the HSR Act.

Key Terms of the Voting Agreement (Page 151)

        As more fully described in this proxy statement/prospectus and as set forth in the voting agreement, in connection with the execution of the merger agreement, the Oaktree shareholders entered into the voting agreement with Sinclair, pursuant to which, prior to the earlier of the closing of the transaction or the termination of the merger agreement, the Oaktree shareholders agreed to vote all of their shares of Tribune Class A common stock (i) in favor of the approval of the approval and adoption of the merger agreement and the transactions contemplated thereby, including the merger and (ii) against other acquisition proposals and certain other actions and transactions, as described in the voting agreement. The Oaktree shareholders also agreed to certain transfer restrictions with respect to their Tribune Class A common stock, which restrictions last until the approval of the merger by the Tribune shareholders or the termination of the merger agreement, and to refrain from solicitation of other acquisition proposals prior to the earlier of the closing of the transaction or the termination of the merger agreement. See "The Agreements—Description of the Voting and Support Agreement" beginning on page 151 for more detail. The Oaktree shareholders hold approximately 16.3% of the outstanding shares of Tribune Class A common stock as of May 4, 2017.

Financing of the Transaction (Page 145)

        On May 8, 2017, in connection with the merger agreement, Sinclair and Sinclair Television Group, Inc., a wholly-owned subsidiary of Sinclair, which we refer to as "STG," entered into a (i) commitment letter, which we refer to as the "credit facilities commitment letter" (as further amended and restated) and (ii) a bridge loan commitment letter, which we refer to as the "bridge facility commitment letter" (as further amended and restated) and together with the credit facilities commitment letter, the "debt commitment letters," in each case with JPMorgan Chase Bank, N.A., which we refer to as "JPMorgan," Royal Bank of Canada, which we refer to as "Royal Bank," RBC Capital Markets, which we refer to as "RBCCM" and, together with Royal Bank, "RBC," Deutsche Bank AG New York Branch, which we refer to as "DBNY," and Deutsche Bank Securities Inc., which we refer to as "DBSI" and, together with DBNY, "Deutsche Bank," and certain of their respective affiliates, for commitments with respect to the financing required by Sinclair to consummate the merger and to refinance certain indebtedness of STG and Tribune.

        The financing under the debt commitment letters, the availability of which is contingent on the satisfaction of certain conditions, including the closing of the transaction, provides for credit facilities in an aggregate principal amount of up to $5,632 million, consisting of: (i) a senior secured term B loan facility in an aggregate principal amount of up to $4,847 million (which will be reduced to $3,747 million as a result of the consent solicitation described below) and (ii) a senior unsecured bridge

loan facility in an aggregate principal amount of up to $785 million available to the extent STG does not issue senior unsecured notes or other securities with an aggregate principal amount of at least $785 million on or prior to the consummation of the transaction.

        The credit facilities commitment letter also provides for the syndication of a senior secured revolving credit facility in an aggregate principal amount of up to $225 million, but such secured revolving credit facility is not required by Sinclair to consummate the transaction.

        The facilities to be provided under the debt commitment letters will bear interest at LIBOR plus an applicable margin. The senior secured credit facilities to be provided under the credit facilities commitment letter will be secured by liens on substantially all of STG's assets and will be guaranteed by, and secured by the assets of, certain of its subsidiaries. Sinclair and/or an affiliate of Sinclair may be a co-borrower under the facilities to be provided under the debt commitment letters. The one-year senior unsecured bridge facility of up to $785 million, which we refer to as the "bridge facility," to be provided under the bridge facility commitment letter will be unsecured but guaranteed by the same guarantors as under the senior secured facilities. Various economic and other terms of the financing under the debt commitment letters are subject to change in the process of syndication as set forth in the debt commitment letters.

        In connection with the transaction, the indebtedness outstanding under Tribune's existing credit facility will be repaid and the commitments thereunder terminated at or prior to the closing of the transaction. However, Tribune's 5.875% Senior Notes due 2022, which we refer to as the "Tribune notes," in the principal amount of $1,100 million, are expected to remain outstanding after the consummation of the transaction. On June 13, 2017, Tribune commenced a consent solicitation, seeking consents from the holders of Tribune notes to amend certain provisions of the indenture governing the Tribune notes, which we refer to as the "Tribune indenture," to (i) eliminate any requirement for Tribune to make a "Change of Control Offer," as defined in the Tribune indenture, to holders of Tribune notes in connection with the transactions, (ii) clarify the treatment under the Tribune indenture of the proposed structure of the transactions and to facilitate the integration of Tribune and its subsidiaries and the Tribune notes with and into Sinclair's debt capital structure, and (iii) eliminate the expense associated with producing and filing with the SEC separate financial reports for STG, as successor issuer of the Tribune notes, if Sinclair or any other parent entity of the successor issuer of the Tribune notes, in its sole discretion, provides an unconditional guarantee of the payment obligations of the successor issuer under the Tribune notes. On June 22, 2017, Tribune announced that it had obtained the requisite consents and had executed a supplemental indenture to amend these provisions of the Tribune indenture. Because the requisite consents were obtained, the aggregate principal amount of the senior secured term B loan facility will be reduced by $1,100 million to $3,747 million in accordance with the debt commitment letters.

        On May 14, 2017, the debt commitment letters were amended and restated to adjust certain of the commitments described thereunder in the event that STG issues senior unsecured notes in an offering in excess of the bridge facility amount of $785 million and to provide additional flexibility regarding the allocation of the commitments for the facilities under the debt commitment letters.

Regulatory Approvals Required for the Merger (Page 118)

        The closing of the transaction is conditioned, among other things, on the expiration or termination of the waiting period under the HSR Act and the receipt of the FCC consent to the transfers of control and assignments in connection with the transaction, which we refer to as the "FCC consent." Sinclair and Tribune filed the Notification and Report Forms on May 30, 2017 with the U.S. Federal Trade Commission, which we refer to as the "FTC," and with the Antitrust Division of the Department of Justice, which we refer to as the "Antitrust Division." On June 29, 2017, Sinclair voluntarily withdrew

its initial Notification and Report Forms filed on May 30, 2017 prior to the end of the initial 30-day waiting period and intends to refile the Notification and Report Forms on July 3, 2017.

        The applications for FCC consent to the transaction were filed on June 26, 2017, and public notice of the filing of the applications will occur on [            ]. The applications will come off public notice on [            ]. FCC consent to the transaction may be delayed or otherwise impacted by (1) petitions to deny the applications, if any, that are filed by [            ], or (2) litigation pending in the U.S. Court of Appeals for the D.C. Circuit challenging the FCC's reinstatement of a Commission rule that discounts by half the audience reach of UHF stations for purposes of determining compliance with national audience reach limitations.

        The timing or outcome of the FCC regulatory process cannot be predicted.

        For additional information relating to the regulatory approvals, see "Transaction Summary—Regulatory Approvals" beginning on page 118, and "The Agreements—Description of the Merger Agreement—Efforts to Consummate the Transaction" beginning on page 142.

Material U.S. Federal Income Tax Consequences of the Merger (Page 122)

        The exchange of shares of Tribune common stock by a Tribune shareholder for cash and shares of Sinclair Class A common stock in the merger will be a taxable transaction for U.S. federal income tax purposes. Accordingly, any Tribune shareholder that is a U.S. Holder (as defined in the section entitled "Material U.S. Federal Income Tax Consequences of the Merger—U.S. Holders") generally will recognize gain or loss for U.S. federal income tax purposes in an amount equal to the difference, if any, between (1) the sum of the amount of cash and the fair market value as of the effective time of the merger of the shares of Sinclair Class A common stock received in the merger and (2) the U.S. Holder's adjusted tax basis in the shares of Tribune common stock exchanged in the merger.

        Any such gain or loss generally will be capital gain or loss and generally will be long-term capital gain or loss if the U.S. Holder's holding period in the Tribune common stock immediately prior to the merger is more than one year. For U.S. Holders that are individuals, estates or trusts, long-term capital gain generally is taxed at preferential rates. The deductibility of capital losses is subject to limitations.

        A U.S. Holder will have a tax basis in the shares of Sinclair Class A common stock received in the merger equal to the fair market value of such shares as of the effective time of the merger. A U.S. Holder's holding period for shares of Sinclair Class A common stock received in exchange for shares of Tribune common stock in the merger will begin on the date immediately following the date on which the merger closes. We refer to the date on which the merger closes as the "closing date."

        A Non-U.S. Holder (as defined in the section entitled "Material U.S. Federal Income Tax Consequences of the Merger—Non-U.S. Holders") generally will not be subject to U.S. federal income tax with respect to the exchange of shares of Tribune common stock for cash and shares of Sinclair Class A common stock in the merger unless such Non-U.S. Holder has certain connections to the United States as described in "Material U.S. Federal Income Tax Consequences of the Merger—Non-U.S. Holders." A Non-U.S. Holder may be subject to backup withholding with respect to payments made pursuant to the merger unless such Non-U.S. Holder certifies that it is not a U.S. person or otherwise establishes an exemption.

        Each Tribune shareholder should consult its own tax advisor to determine the particular tax consequences of the merger to such Tribune shareholder in light of such Tribune shareholder's particular circumstances.

Interests of Tribune's Directors and Executive Officers in the Merger (Page 109)

        In considering the recommendation of the Tribune board that Tribune shareholders vote to adopt the merger agreement, you should be aware that some of Tribune's directors and executive officers have interests in the merger that may be different from, or in addition to, the interests of Tribune shareholders generally. Interests of directors and officers that may be different from or in addition to the interests of Tribune shareholders include, but are not limited to:

•

certain outstanding equity awards granted to Tribune's executive officers and directors will be subject to accelerated vesting on the terms and conditions specified below, and converted in connection with the completion of the merger into the right to receive an amount in cash equal to the merger consideration. Certain restricted stock units in respect of Tribune common stock will be converted into cash-settled restricted stock units in respect of Sinclair common stock that will be subject to accelerated vesting upon certain terminations of employment, as describe below;



•

Tribune is party to employment agreements with each of its executive officers (other than its interim Chief Executive Officer), which provide for severance payments and benefits in connection with a termination of employment by Tribune without cause or by the executive officer for good reason, as well as certain change in control enhancements and benefits in connection with such a termination following the completion of the merger, but, except as described below, their entitlements to severance benefits are not affected by the merger;



•

certain Tribune employees (including the executive officers) and certain directors may be eligible to receive transaction or retention bonuses in connection with and following the completion of the merger, subject to their continued employment with Tribune (although, as of the date of this proxy statement, while the Company adopted this transaction and retention bonus program on April 24, 2017, no determinations have been made as to (i) whether any executive officer or director will receive an award or (ii) the amounts of any such potential awards); and



•

Tribune's directors and executive officers are entitled to continued indemnification and insurance coverage under the merger agreement.

        These interests are discussed in more detail in the section entitled "Transaction Summary—Interests of Tribune's Directors and Executive Officers in the Merger" beginning on page 109 of this proxy statement/prospectus.

        The Tribune board was aware of these interests and considered them, among other matters, in approving the merger agreement and the transactions contemplated by the merger agreement and in recommending that the Tribune shareholders vote "FOR" the merger proposal.

Voting by Tribune's Directors and Executive Officers

        As of March 15, 2017, the directors and executive officers of Tribune beneficially owned, in the aggregate, 475,548 shares (or less than 1%) of Tribune Class A common stock and no shares of Tribune Class B common stock. The directors and executive officers of Tribune have informed Tribune that they currently intend to vote all of their shares of Tribune Class A common stock for all of the proposals to be voted on at the special meeting.

Appraisal Rights (Page 153)

        Tribune shareholders are entitled to appraisal rights under Section 262 of the DGCL, provided they follow procedures and satisfy the conditions set forth in Section 262 of the DGCL. See "Appraisal Rights." In addition, a copy of Section 262 of the DGCL is attached as Annex E to this proxy

statement/prospectus. Failure to strictly comply with Section 262 of the DGCL may result in your waiver of, or inability to, exercise appraisal rights.

Comparison of Shareholder Rights (Page 174)

        The rights of the holders of Sinclair's Class A common stock are governed by Sinclair's current articles of incorporation and bylaws, as well as the Maryland General Corporation Law, which we refer to as the "MGCL." The rights of the Tribune shareholders are governed by Tribune's current certificate of incorporation and bylaws, as well as the DGCL. Upon closing of the transaction, the rights of the Tribune shareholders will be governed by Sinclair's articles of incorporation and bylaws, as well as the MGCL and will differ in some respects from their rights under Tribune's certificate of incorporation and bylaws and the DGCL. For more information regarding a comparison of such rights, see "Comparison of Shareholder Rights" on page 174.

Risk Factors (Page 35)

        You should consider all the information contained in or incorporated by reference into this proxy statement/prospectus in deciding how to vote for the proposals presented in this proxy statement/prospectus.

SELECTED CONSOLIDATED HISTORICAL FINANCIAL DATA OF SINCLAIR

        The following table sets forth Sinclair's selected consolidated historical financial data as of the dates and for the periods indicated. The selected consolidated historical financial data as of March 31, 2017 and for the three months ended March 31, 2017 and March 31, 2016 have been derived from Sinclair's unaudited condensed consolidated financial statements and related notes which are incorporated herein by reference. The data as of March 31, 2017 and for the three months ended March 31, 2017 and March 31, 2016, in the opinion of Sinclair's management include all adjustments, consisting only of normal recurring adjustments, necessary for a fair statement of the results for the unaudited interim periods. The selected consolidated historical financial data as of December 31, 2016 and December 31, 2015 and for each of the years ended December 31, 2016, December 31, 2015 and December 31, 2014 have been derived from Sinclair's audited consolidated financial statements and related notes which are incorporated herein by reference. The selected consolidated historical financial data as of December 31, 2014, December 31, 2013, December 31, 2012 and for the years ended December 31, 2013 and December 31, 2012 have been derived from Sinclair's audited consolidated financial statements and related notes not required to be incorporated by reference herein. The selected consolidated historical financial data are qualified in their entirety by, and should be read in conjunction with, "Management's Discussion and Analysis of Financial Condition and Results of Operations" and Sinclair's audited consolidated financial statements and unaudited condensed consolidated financial statements and the related notes thereto included in Sinclair's Annual Report on Form 10-K for the year ended December 31, 2016 and Quarterly Report on Form 10-Q for the quarterly period ended March 31, 2017, respectively, each of which is incorporated herein by reference. See "Where You Can Find More Information" beginning on page 186. Sinclair's consolidated historical financial data may not be indicative of the future performance of Sinclair.

STATEMENTS OF OPERATIONS DATA
(In thousands, except per share data)

SELECTED CONSOLIDATED HISTORICAL FINANCIAL DATA OF TRIBUNE

        The following table sets forth Tribune's selected consolidated historical financial data as of the dates and for the periods indicated and reflects the January 31, 2017 sale of Tribune's equity interest in substantially all of its digital and data business operations and the August 4, 2014 spin-off of the assets and certain liabilities of the businesses primarily related to Tribune's principal publishing operations, other than certain real estate and other assets. The selected consolidated historical financial data as of March 31, 2017 and for the three months ended March 31, 2017 and March 31, 2016 have been derived from Tribune's unaudited condensed consolidated financial statements and related notes, which are incorporated herein by reference. The data for the three months ended March 31, 2017 and March 31, 2016, in the opinion of Tribune's management, include all adjustments, consisting only of normal recurring adjustments, necessary for a fair statement of the results for the unaudited interim periods. The selected consolidated historical financial data as of December 31, 2016 and December 31, 2015 and for each of the years ended December 31, 2016, December 31, 2015 and December 28, 2014 have been derived from Tribune's audited consolidated financial statements and related notes which are incorporated herein by reference. The selected consolidated historical financial data as of December 28, 2014, December 29, 2013, December 31, 2012 and December 30, 2012 and for the years ended December 29, 2013 and December 30, 2012 and for December 31, 2012 have been derived from Tribune's audited consolidated financial statements and related notes not incorporated by reference herein. The selected consolidated historical financial data are qualified in their entirety by, and should be read in conjunction with, "Management's Discussion and Analysis of Financial Condition and Results of Operations" and Tribune's audited consolidated financial statements and unaudited condensed consolidated financial statements and the related notes thereto included in Tribune's Annual Report on Form 10-K for the year ended December 31, 2016 and Quarterly Report on Form 10-Q for the quarterly period ended March 31, 2017, respectively, each of which is incorporated herein by reference. See "Where You Can Find More Information" beginning on page 186. Tribune's consolidated historical financial data may not be indicative of the future performance of Tribune or Sinclair.

        In connection with its emergence from bankruptcy on December 31, 2012, Tribune and its business operations as conducted on or prior to December 30, 2012 are referred to collectively as the "Predecessor" and Tribune and its business operations as conducted on or subsequent to December 31, 2012 are referred to collectively as the "Successor." For a discussion of the distinction between Predecessor and Successor, see Note 3 to Tribune's audited consolidated financial statements included

in its Annual Report on Form 10-K for the year ended December 31, 2016, which is incorporated by reference herein.

SUMMARY UNAUDITED PRO FORMA CONDENSED COMBINED FINANCIAL INFORMATION

        The following summary unaudited pro forma condensed combined financial information gives effect to the merger. The selected unaudited pro forma combined statement of operations data for the year ended December 31, 2016 and the three months ended March 31, 2017, gives effect to the merger as if it had occurred on January 1, 2016. The selected unaudited pro forma combined balance sheet data as of March 31, 2017 gives effect to the merger as if it had occurred on March 31, 2017. See "Unaudited Pro Forma Condensed Combined Financial Information" beginning on page 158.

        The summary unaudited pro forma financial information for the merger has been developed from, and should be read in conjunction with, the Sinclair and Tribune unaudited interim condensed consolidated financial statements contained in the Sinclair and Tribune Quarterly Reports on Form 10-Q for the three months ended March 31, 2017, respectively, and the Sinclair and Tribune audited consolidated financial statements contained in the Sinclair and Tribune Annual Reports on Form 10-K for the year ended December 31, 2016, respectively, each of which is incorporated by reference into this proxy statement/prospectus. See "Where You Can Find More Information" beginning on page 186.

        The pro forma adjustments give effect to events that are (1) directly attributable to the merger, (2) factually supportable and (3) with respect to the pro forma statement of operations data, expected to have a continuing impact on the results of Sinclair after the closing of the transaction. In order to obtain approval of the transaction from the FCC and/or under the HSR Act, Sinclair and/or Tribune may be required to divest certain stations that they currently own. An estimated result of these divestitures has not been reflected in the pro forma adjustments. However, the issuance of debt required to fund the transaction has been reflected in the pro forma adjustments.

        The summary unaudited pro forma financial information was prepared using the acquisition method of accounting with Sinclair treated as the accounting acquirer and therefore, the historical basis of Sinclair's assets and liabilities is not affected by the transaction. For purposes of developing the pro forma financial information, the acquired Tribune assets, including identifiable intangible assets, and liabilities assumed have been recorded at their estimated fair values with the excess purchase price assigned to goodwill. The estimated fair values assigned in this summary unaudited pro forma financial information are preliminary and represent Sinclair's current best estimate of fair value and are subject to revision. The summary unaudited pro forma financial information is provided for informational purposes only and is based on available information and assumptions that Sinclair believes are reasonable. It does not purport to represent what the actual consolidated results of operations or the consolidated financial position of Sinclair would have been had the transaction occurred on the dates indicated, nor is it necessarily indicative of future consolidated results of operations or consolidated financial position. The actual financial position and results of operations will differ, perhaps significantly, from the pro forma amounts reflected herein due to a variety of factors, including access to additional information, changes in the preliminary estimated value of acquired assets and liabilities not currently identified and changes in operating results following the date of the pro forma financial information.

        The summary unaudited pro forma financial information does not reflect any cost savings, divestitures, or other synergies discussed in "Transaction Summary—Tribune's Reasons for the Transaction and Recommendation of the Tribune Board" beginning on page 66, that the management

of Sinclair and Tribune believe could have been achieved had the transaction been completed on the dates assumed.

COMPARATIVE PER SHARE DATA

        The following table presents selected historical per share information of Sinclair and Tribune as of and for the three month period ended March 31, 2017 and as of and for the year ended December 31, 2016. Also set forth below is information for Sinclair on an unaudited pro forma basis, calculated using the acquisition method of accounting, as if the transaction had been effective as of January 1, 2016, the first day of the year ended December 31, 2016, in the case of earnings per share, which we refer to as "pro forma combined" information.

        The historical per share information of Sinclair below is derived from the unaudited condensed consolidated financial statements for Sinclair as of, and for the three months ended, March 31, 2017 that are incorporated by reference into this proxy statement/prospectus from Sinclair's Quarterly Report on Form 10-Q for the quarterly period ended March 31, 2017 and from the audited consolidated financial statements of Sinclair as of, and for the year ended, December 31, 2016 that are incorporated by reference into this proxy statement/prospectus from Sinclair's Annual Report on Form 10-K for the year ended December 31, 2016.

        The historical per share information of Tribune below is derived from the unaudited condensed consolidated financial statements for Tribune as of, and for the three months ended, March 31, 2017 that are incorporated by reference into this proxy statement/prospectus from Tribune's Quarterly Report on Form 10-Q for the quarterly period ended March 31, 2017 and from the audited consolidated financial statements of Tribune as of, and for the year ended, December 31, 2016 that are incorporated by reference into this proxy statement/prospectus from Tribune's Annual Report on Form 10-K for the year ended December 31, 2016.

        The pro forma combined information presented below is calculated using the acquisition method of accounting, as if the transaction had been effective on January 1, 2016 in the case of earnings and dividends per share data and on March 31, 2017, in the case of book value per share data.

        The pro forma combined information is for illustrative purposes only and is not necessarily indicative of actual or future financial positions or results of operations that would have been realized if the transaction had been completed as of the dates indicated or will be realized upon the completion of the transaction.

        The Tribune equivalent per share information is calculated by multiplying the pro forma combined per share amounts for Sinclair after the closing of the transaction by 0.2300, which represents the ratio of shares of Sinclair Class A common stock to be received for each share of Tribune common stock in the merger. This calculation does not take into account the cash consideration to be received by holders of Tribune common stock in the merger.

        You should read the information in this section in conjunction with the "Summary Unaudited Pro Forma Condensed Combined Financial Information" beginning on page 28, with Sinclair's historical consolidated financial statements and related notes that Sinclair has previously filed with the SEC and which are incorporated in this joint proxy statement/prospectus by reference, and with Tribune's historical consolidated financial statements and related notes that Tribune has previously filed with the SEC and which are incorporated in this joint proxy statement/prospectus by reference. See

"Incorporation of Certain Documents by Reference" beginning on page 184 and "Where You Can Find More Information" beginning on page 186.

COMPARATIVE PER SHARE MARKET PRICE AND DIVIDEND INFORMATION

Market Prices

        The following table sets forth the closing prices per share of the Sinclair Class A common stock, which trades on the NASDAQ under the symbol "SBGI," the Tribune Class A common stock (which is convertible at any time (subject to limitations in Tribune's certificate of incorporation) into Tribune Class B common stock), which trades on the NYSE under the symbol "TRCO," and the Tribune Class B common stock (which is convertible at any time (subject to limitations in Tribune's certificate of incorporation) into Tribune Class A common stock), quoted on the OTC Pink market under the symbol "TRBAB" on the following dates:

•

May 5, 2017, the last full trading day before the announcement of the execution of the merger agreement; and



•

[          ], 2017, the last full trading day for which this information could reasonably be calculated before the date of this proxy statement/prospectus.

There is no established trading market for the Class B Common Stock, par value $0.01, of Sinclair, which we refer to as the "Sinclair Class B common stock" (which is convertible at any time (subject to the limitations in Sinclair's articles of incorporation) into Sinclair Class A common stock).

        Tribune shareholders will not receive any merger consideration for their Tribune common stock until the merger is completed, which may be a substantial time period after the special meeting. In addition, the exchange ratio for determining the number of shares of Sinclair Class A common stock that the Tribune shareholders will receive in the merger is fixed at 0.2300 and, as such, the stock consideration will not be adjusted for changes in the market price of the Sinclair Class A common stock or the Tribune common stock. Therefore, the market value of the Sinclair Class A common stock that the Tribune shareholders will receive on the closing of the transaction will depend on the market value of the Sinclair Class A common stock immediately before the transaction is completed and could vary significantly from the market value on the date of the announcement of the merger agreement, the date that this proxy statement/prospectus was first mailed to Tribune shareholders or the date of the special meeting.

        The following table sets forth, for the periods indicated, the high and low sales prices per share of Sinclair Class A common stock, Tribune Class A common stock and Tribune Class B common stock as reported on the NASDAQ (in the case of Sinclair Class A common stock), the NYSE (in the case of

Tribune Class A common stock) and the OTC Pink market (in the case of Tribune Class B common stock) and the regular dividends paid out during these periods.