UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549


                                  SCHEDULE 13G


                    Under the Securities Exchange Act of 1934

                               (Amendment No. 2)*

                                 Power-One, Inc.
                                (Name of Issuer)

                    Common Stock, par value $0.001 per share
                         (Title of Class of Securities)

                                    739308104
                                 (CUSIP Number)

                                December 31, 2009
             (Date of Event Which Requires Filing of this Statement)


     Check the appropriate box to designate the rule pursuant to which this
Schedule is filed:
     [ ] Rule 13d-1(b)
     [X] Rule 13d-1(c)
     [ ] Rule 13d-1(d)





----------------
     *The remainder of this cover page shall be filled out for a reporting
person's initial filing on this form with respect to the subject class of
securities, and for any subsequent amendment containing information which would
alter the disclosures provided in a prior cover page.

     The information required in the remainder of this cover page shall not be
deemed to be "filed" for purpose of Section 18 of the Securities Exchange Act of
1934 ("Act") or otherwise subject to the liabilities of that section of the Act
but shall be subject to all other provisions of the Act (however, see the
Notes).


                               Page 1 of 12 Pages





CUSIP No. 739308104                  13G                   Page 2 of 12 Pages

-----------------------------------------------------------------------
     (1)    NAMES OF REPORTING PERSONS

            Highbridge International LLC
-----------------------------------------------------------------------
     (2)    CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP
            (see instructions)
                                                               (a) [X]
                                                               (b) [ ]
-----------------------------------------------------------------------
     (3)    SEC USE ONLY
-----------------------------------------------------------------------
     (4)    CITIZENSHIP OR PLACE OF ORGANIZATION

            Cayman Islands, British West Indies
-----------------------------------------------------------------------
NUMBER OF      (5)  SOLE VOTING POWER
                    0
SHARES         --------------------------------------------------------

BENEFICIALLY   (6)  SHARED VOTING POWER
                    $6,000,000 aggregate principal amount of 8.0%
OWNED BY            Senior Secured Convertible Notes due June 17,
                    2013, convertible into 3,000,000 shares of Common
EACH                Stock
               --------------------------------------------------------
REPORTING
               (7)  SOLE DISPOSITIVE POWER
PERSON WITH         0
               --------------------------------------------------------

               (8)  SHARED DISPOSITIVE POWER
                    $6,000,000 aggregate principal amount of 8.0%
                    Senior Secured Convertible Notes due June 17,
                    2013, convertible into 3,000,000 shares of Common
                    Stock
-----------------------------------------------------------------------
     (9)    AGGREGATE AMOUNT BENEFICIALLY OWNED
            BY EACH REPORTING PERSON
            $6,000,000 aggregate principal amount of 8.0% Senior Secured
            Convertible Notes due June 17, 2013, convertible into
            3,000,000 shares of Common Stock
-----------------------------------------------------------------------
     (10)   CHECK BOX IF THE AGGREGATE AMOUNT
            IN ROW (9) EXCLUDES CERTAIN SHARES (see instructions)
                                                                    [ ]
-----------------------------------------------------------------------
     (11)   PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)
            3.29%
-----------------------------------------------------------------------
     (12)   TYPE OF REPORTING PERSON (see instructions)
            OO
-----------------------------------------------------------------------





CUSIP No. 739308104                  13G                   Page 3 of 12 Pages


-----------------------------------------------------------------------
     (1)    NAMES OF REPORTING PERSONS

            STAR L.P. (a statistical arbitrage strategy)
-----------------------------------------------------------------------
     (2)    CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP
            (see instructions)
                                                               (a) [X]
                                                               (b) [ ]
-----------------------------------------------------------------------
     (3)    SEC USE ONLY
-----------------------------------------------------------------------
     (4)    CITIZENSHIP OR PLACE OF ORGANIZATION

            Cayman Islands, British West Indies
-----------------------------------------------------------------------
NUMBER OF      (5)  SOLE VOTING POWER
                    0
SHARES         --------------------------------------------------------

BENEFICIALLY   (6)  SHARED VOTING POWER
                    82,211 shares of Common Stock
OWNED BY       --------------------------------------------------------

EACH           (7)  SOLE DISPOSITIVE POWER
                    0
REPORTING      --------------------------------------------------------

PERSON WITH    (8)  SHARED DISPOSITIVE POWER
                    82,211 shares of Common Stock
-----------------------------------------------------------------------
     (9)    AGGREGATE AMOUNT BENEFICIALLY OWNED
            BY EACH REPORTING PERSON
            82,211 shares of Common Stock
-----------------------------------------------------------------------
     (10)   CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9)
            EXCLUDES CERTAIN SHARES (see instructions)
                                                                    [ ]
-----------------------------------------------------------------------
     (11)   PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)
            0.09%
-----------------------------------------------------------------------
     (12)   TYPE OF REPORTING PERSON (see instructions)
            PN
-----------------------------------------------------------------------





CUSIP No. 739308104                  13G                   Page 4 of 12 Pages


-----------------------------------------------------------------------

     (1)    NAMES OF REPORTING PERSONS

            Highbridge Statistical Opportunities Master Fund, L.P.
-----------------------------------------------------------------------
     (2)    CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP
            (see instructions)
                                                               (a) [X]
                                                               (b) [ ]
-----------------------------------------------------------------------
     (3)    SEC USE ONLY
-----------------------------------------------------------------------
     (4)    CITIZENSHIP OR PLACE OF ORGANIZATION

            Cayman Islands, British West Indies
-----------------------------------------------------------------------
NUMBER OF      (5)  SOLE VOTING POWER
                    0
SHARES         --------------------------------------------------------

BENEFICIALLY   (6)  SHARED VOTING POWER
                    145,322 shares of Common Stock
OWNED BY       --------------------------------------------------------

EACH           (7)  SOLE DISPOSITIVE POWER
                    0
REPORTING      --------------------------------------------------------

PERSON WITH    (8)  SHARED DISPOSITIVE POWER
                    145,322 shares of Common Stock
-----------------------------------------------------------------------
     (9)    AGGREGATE AMOUNT BENEFICIALLY OWNED
            BY EACH REPORTING PERSON
            145,322 shares of Common Stock
-----------------------------------------------------------------------
     (10)   CHECK BOX IF THE AGGREGATE AMOUNT
            IN ROW (9) EXCLUDES CERTAIN SHARES (see instructions)
                                                                    [ ]
-----------------------------------------------------------------------
     (11)   PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)
            0.16%
-----------------------------------------------------------------------
     (12)   TYPE OF REPORTING PERSON (see instructions)
            PN
-----------------------------------------------------------------------





CUSIP No. 739308104                  13G                   Page 5 of 12 Pages


-----------------------------------------------------------------------

     (1)    NAMES OF REPORTING PERSONS

            Highbridge Convertible Opportunities Master Fund, L.P.
-----------------------------------------------------------------------
     (2)    CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP
            (see instructions)
                                                               (a) [X]
                                                               (b)  [ ]
-----------------------------------------------------------------------
     (3)    SEC USE ONLY
-----------------------------------------------------------------------
     (4)    CITIZENSHIP OR PLACE OF ORGANIZATION

            Cayman Islands, British West Indies
-----------------------------------------------------------------------
NUMBER OF      (5)  SOLE VOTING POWER
                    0
SHARES         --------------------------------------------------------

BENEFICIALLY   (6)  SHARED VOTING POWER
                    0
OWNED BY       --------------------------------------------------------

EACH           (7)  SOLE DISPOSITIVE POWER
                    0
REPORTING      --------------------------------------------------------

PERSON WITH    (8)  SHARED DISPOSITIVE POWER
                    0
-----------------------------------------------------------------------
     (9)    AGGREGATE AMOUNT BENEFICIALLY OWNED
            BY EACH REPORTING PERSON
            0
-----------------------------------------------------------------------
     (10)   CHECK BOX IF THE AGGREGATE AMOUNT
            IN ROW (9) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS)
                                                                    [ ]
-----------------------------------------------------------------------
     (11)   PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)
            0%
-----------------------------------------------------------------------
     (12)   TYPE OF REPORTING PERSON (SEE INSTRUCTIONS)
            PN
-----------------------------------------------------------------------







CUSIP No. 739308104                  13G                   Page 6 of 12 Pages


-----------------------------------------------------------------------
     (1)    NAMES OF REPORTING PERSONS

            Highbridge Capital Management, LLC
-----------------------------------------------------------------------
     (2)    CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP
            (see instructions)
                                                               (a) [X]
                                                               (b) [ ]
-----------------------------------------------------------------------
     (3)    SEC USE ONLY
-----------------------------------------------------------------------
     (4)    CITIZENSHIP OR PLACE OF ORGANIZATION

            State of Delaware
-----------------------------------------------------------------------
NUMBER OF      (5)  SOLE VOTING POWER
                    0
SHARES         --------------------------------------------------------

BENEFICIALLY   (6)  SHARED VOTING POWER
                    $6,000,000 aggregate principal amount of 8.0%
OWNED BY            Senior Secured Convertible Notes due June 17,
                    2013, convertible into 3,000,000 shares of Common
EACH                Stock

REPORTING           227,533 shares of Common Stock
               --------------------------------------------------------
PERSON WITH
               (7)  SOLE DISPOSITIVE POWER
                    0
               --------------------------------------------------------

               (8)  SHARED DISPOSITIVE POWER
                    $6,000,000 aggregate principal amount of 8.0%
                    Senior Secured Convertible Notes due June 17,
                    2013, convertible into 3,000,000 shares of Common
                    Stock

                    227,533 shares of Common Stock
-----------------------------------------------------------------------
     (9)    AGGREGATE AMOUNT BENEFICIALLY OWNED
            BY EACH REPORTING PERSON
            $6,000,000 aggregate principal amount of 8.0% Senior Secured
            Convertible Notes due June 17, 2013, convertible into
            3,000,000 shares of Common Stock

            227,533 shares of Common Stock
-----------------------------------------------------------------------
     (10)   CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9)
            EXCLUDES CERTAIN SHARES (see instructions)
                                                                    [ ]
-----------------------------------------------------------------------
     (11)   PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)
            3.54%
-----------------------------------------------------------------------
     (12)   TYPE OF REPORTING PERSON (see instructions)
            OO
-----------------------------------------------------------------------





CUSIP No. 739308104                  13G                   Page 7 of 12 Pages


-----------------------------------------------------------------------
     (1)    NAMES OF REPORTING PERSONS

            Glenn Dubin
-----------------------------------------------------------------------
     (2)    CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP
            (see instructions)
                                                               (a) [X]
                                                               (b) [ ]
-----------------------------------------------------------------------
     (3)    SEC USE ONLY
-----------------------------------------------------------------------
     (4)    CITIZENSHIP OR PLACE OF ORGANIZATION

            United States
-----------------------------------------------------------------------
NUMBER OF      (5)  SOLE VOTING POWER
                    0
SHARES         --------------------------------------------------------

BENEFICIALLY   (6)  SHARED VOTING POWER
                    $6,000,000 aggregate principal amount of 8.0%
OWNED BY            Senior Secured Convertible Notes due June 17,
                    2013, convertible into 3,000,000 shares of Common
EACH                Stock

REPORTING           227,533 shares of Common Stock
               --------------------------------------------------------
PERSON WITH
               (7)  SOLE DISPOSITIVE POWER
                    0
               --------------------------------------------------------

               (8)  SHARED DISPOSITIVE POWER
                    $6,000,000 aggregate principal amount of 8.0%
                    Senior Secured Convertible Notes due June 17,
                    2013, convertible into 3,000,000 shares of Common
                    Stock

                    227,533 shares of Common Stock
-----------------------------------------------------------------------
     (9)    AGGREGATE AMOUNT BENEFICIALLY OWNED
            BY EACH REPORTING PERSON
            $6,000,000 aggregate principal amount of 8.0% Senior Secured
            Convertible Notes due June 17, 2013, convertible into
            3,000,000 shares of Common Stock

            227,533 shares of Common Stock
-----------------------------------------------------------------------
     (10)   CHECK BOX IF THE AGGREGATE AMOUNT
            IN ROW (9) EXCLUDES CERTAIN SHARES (see instructions)
                                                                    [ ]
-----------------------------------------------------------------------
     (11)   PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)
            3.54%
-----------------------------------------------------------------------
     (12)   TYPE OF REPORTING PERSON (see instructions)
            IN
-----------------------------------------------------------------------






CUSIP No. 739308104                  13G                   Page 8 of 12 Pages


This Amendment No. 2 (this "Amendment") amends the statement on Schedule 13G
filed on June 20, 2008, as amended by Amendment No. 1 filed on February 9, 2009
(the "Original Schedule 13G" and the Original Schedule 13G as amended, the
"Schedule 13G") with respect to shares of common stock, par value $0.001 per
share (the "Common Stock") of Power-One, Inc., a Delaware corporation (the
"Company"). Capitalized terms used herein and not otherwise defined in this
Amendment have the meanings set forth in the Schedule 13G. This Amendment amends
and restates Items 2(a), 2(b), 2(c), 4 and 5 in their entirety as set forth
below.

Item 2(a).  Name of Person Filing
Item 2(b).  Address of Principal Business Office
Item 2(c).  Citizenship

           HIGHBRIDGE INTERNATIONAL LLC
           c/o Harmonic Fund Services
           The Cayman Corporate Centre, 4th Floor
           27 Hospital Road
           Grand Cayman, Cayman Islands, British West Indies
           Citizenship:  Cayman Islands, British West Indies

           STAR, L.P. (A STATISTICAL ARBITRAGE STRATEGY)
           c/o Harmonic Fund Services
           The Cayman Corporate Centre, 4th Floor
           27 Hospital Road
           Grand Cayman, Cayman Islands, British West Indies
           Citizenship:  Cayman Islands, British West Indies

           HIGHBRIDGE CONVERTIBLE ARBITRAGE MASTER FUND, L.P.
           c/o Harmonic Fund Services
           The Cayman Corporate Centre, 4th Floor
           27 Hospital Road
           Grand Cayman, Cayman Islands, British West Indies
           Citizenship:  Cayman Islands, British West Indies

           HIGHBRIDGE CAPITAL MANAGEMENT, LLC
           40 West 57th Street, 33rd Floor
           New York, New York  10019
           Citizenship:  State of Delaware

           GLENN DUBIN
           c/o Highbridge Capital Management, LLC
           40 West 57th Street, 33rd Floor
           New York, New York 10019
           Citizenship:  United States


Item 4.   Ownership

            Provide the following information regarding the aggregate number and
percentage of the class of securities of the issuer identified in Item 1.

            (a) Amount beneficially owned:

         As of December 31, 2009, (i) Highbridge International LLC beneficially
owned $6,000,000 aggregate principal amount of 8.0% Senior Secured Convertible





CUSIP No. 739308104                  13G                   Page 9 of 12 Pages



Notes due June 17, 2013 (the "Notes"), convertible into 3,000,000 shares of
Common Stock (not counting any accrued and unpaid interest on the Notes), (ii)
STAR, L.P. (a statistical arbitrage strategy) beneficially owned 82,211 shares
of Common Stock, (iii) Highbridge Statistical Opportunities Master Fund, L.P.
beneficially owned 145,322 any shares of Common Stock, (iv) Highbridge
Convertible Opportunities Master Fund, L.P. no longer beneficially owned any
shares of Common Stock and (v) each of Highbridge Capital Management, LLC and
Glenn Dubin may have been deemed the beneficial owner of the $6,000,000
aggregate principal amount of the Notes, convertible into 3,000,000 shares of
Common Stock (not counting any accrued and unpaid interest on the Notes)
beneficially owned by Highbridge International LLC and 227,553 shares of Common
Stock beneficially owned by STAR, L.P. (a statistical arbitrage strategy) and
Highbridge Statistical Opportunities Master Fund, L.P. Pursuant to the terms of
the Notes, Highbridge International LLC cannot convert any of the Notes until
such time as the Reporting Persons would not beneficially own, after any such
conversion, more than 9.99% of the outstanding Common Stock.

         Highbridge Capital Management, LLC is the trading manager of Highbridge
International LLC, STAR, L.P. (a statistical arbitrage strategy), Highbridge
Statistical Opportunities Master Fund, L.P. and Highbridge Convertible
Opportunities Master Fund, L.P. Glenn Dubin is the Chief Executive Officer of
Highbridge Capital Management, LLC. The foregoing should not be construed in and
of itself as an admission by any Reporting Person as to beneficial ownership of
shares of Common Stock owned by another Reporting Person. In addition, each of
Highbridge Capital Management, LLC and Glenn Dubin disclaims beneficial
ownership of shares of Common Stock held by Highbridge International LLC, STAR,
L.P. (a statistical arbitrage strategy) and Highbridge Statistical Opportunities
Master Fund, L.P.

            (b) Percent of class:

         The Company's quarterly report for the quarterly period ended September
27, 2009 filed on Form 10-Q on November 6, 2009, indicates that as of November
5, 2009, there were 88,198,670 shares of Common Stock outstanding. Therefore, as
of December 31, 2009, based on the Company's outstanding shares of Common Stock
and, for purposes of clauses (i) and (v) below, assuming the conversion of the
Notes, (i) Highbridge International LLC may have been deemed to beneficially own
3.29% of the outstanding shares of Common Stock of the Company, (ii) STAR, L.P.
(a statistical arbitrage strategy) may have been deemed to beneficially own
0.09% of the outstanding shares of Common Stock of the Company, (iii) Highbridge
Statistical Opportunities Master Fund, L.P. may have been deemed to beneficially
own 0.16% of the outstanding shares of Common Stock of the Company, (iv)
Highbridge Convertible Opportunities Master Fund, L.P. no longer beneficially
owned any shares of Common Stock of the Company and (v) each of Highbridge
Capital Management, LLC and Glenn Dubin may have been deemed to beneficially own
3.54% of the outstanding shares of Common Stock of the Company. The foregoing
should not be construed in and of itself as an admission by any Reporting Person
as to beneficial ownership of shares of Common Stock owned by another Reporting
Person.

            (c) Number of shares as to which such person has:

                (i) Sole power to vote or to direct the vote

                    0

                (ii) Shared power to vote or to direct the vote





CUSIP No. 739308104                  13G                   Page 10 of 12 Pages

                     See Item 4(a)

                (iii) Sole power to dispose or to direct the disposition of

                           0

                (iv)  Shared power to dispose or to direct the disposition of

                      See Item 4(a)


Item 5.  Ownership of Five Percent or Less of a Class

            If this statement is being filed to report the fact that as of the
date hereof the reporting person has ceased to be the beneficial owner of more
than five percent of the class of securities, check the following: [X]


Exhibits:

Exhibit I: Joint Filing Agreement, dated as of February 8, 2010, by and among
Highbridge International LLC, Highbridge Convertible Opportunities Master Fund,
L.P., Highbridge Capital Management, LLC and Glenn Dubin.





CUSIP No. 739308104                  13G                   Page 11 of 12 Pages


                                   SIGNATURES

            After reasonable inquiry and to the best of its knowledge and
belief, each of the undersigned certifies that the information with respect to
it set forth in this statement is true, complete, and correct.

Dated: February 8, 2010

HIGHBRIDGE CAPITAL MANAGEMENT, LLC        HIGHBRIDGE INTERNATIONAL LLC

                                          By: Highbridge Capital Management, LLC
                                              its Trading Manager

By: /s/ John Oliva
    --------------                        By: /s/ John Oliva
Name: John Oliva                              --------------
                                          Name: John Oliva
Title: Managing Director                  Title: Managing Director


STAR, L.P. (a statistical arbitrage       HIGHBRIDGE STATISTICAL OPPORTUNITIES
strategy)                                 MASTER FUND, L.P.

By: Highbridge Capital Management, LLC    By: Highbridge Capital Management, LLC
    its Trading Manager                       its Trading Manager


By: /s/ John Oliva                        By: /s/ John Oliva
    -------------                             --------------
Name: John Oliva                          Name: John Oliva
Title: Managing Director                  Title: Managing Director

HIGHBRIDGE CONVERTIBLE OPPORTUNITIES
MASTER FUND, L.P.
                                          /s/ Glenn Dubin
By: Highbridge Capital Management, LLC    ---------------
    its Trading Manager                   GLENN DUBIN


By: /s/ John Oliva
    --------------
Name: John Oliva
Title: Managing Director






CUSIP No. 739308104                  13G                   Page 12 of 12 Pages


                                    EXHIBIT I

                             JOINT FILING AGREEMENT

This will confirm the agreement by and among the undersigned that the Schedule
13G filed with the Securities and Exchange Commission on or about the date
hereof with respect to the beneficial ownership by the undersigned of the shares
of Common Stock, $0.001 par value, of Power-One, Inc., is being filed, and all
amendments thereto will be filed, on behalf of each of the persons and entities
named below in accordance with Rule 13d-1(k) under the Securities Exchange Act
of 1934, as amended. This Agreement may be executed in two or more counterparts,
each of which shall be deemed an original, but all of which together shall
constitute one and the same instrument.

Dated: February 8, 2010

HIGHBRIDGE CAPITAL MANAGEMENT, LLC        HIGHBRIDGE INTERNATIONAL LLC

                                          By: Highbridge Capital Management, LLC
                                              its Trading Manager

By: /s/ John Oliva
    --------------                        By: /s/ John Oliva
Name: John Oliva                              --------------
                                          Name: John Oliva
Title: Managing Director                  Title: Managing Director


STAR, L.P. (a statistical arbitrage       HIGHBRIDGE STATISTICAL OPPORTUNITIES
strategy)                                 MASTER FUND, L.P.

By: Highbridge Capital Management, LLC    By: Highbridge Capital Management, LLC
    its Trading Manager                       its Trading Manager


By: /s/ John Oliva                        By: /s/ John Oliva
    -------------                             --------------
Name: John Oliva                          Name: John Oliva
Title: Managing Director                  Title: Managing Director

HIGHBRIDGE CONVERTIBLE OPPORTUNITIES
MASTER FUND, L.P.
                                          /s/ Glenn Dubin
By: Highbridge Capital Management, LLC    ---------------
    its Trading Manager                   GLENN DUBIN


By: /s/ John Oliva
    --------------
Name: John Oliva
Title: Managing Director