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


                                  SCHEDULE 13G

                    UNDER THE SECURITIES EXCHANGE ACT OF 1934
                               (AMENDMENT NO. 2)*

                         UNITED THERAPEUTICS CORPORATION
--------------------------------------------------------------------------------
                                (Name of Issuer)

                     Common Stock, $0.01 Par Value Per Share
--------------------------------------------------------------------------------
                         (Title of Class of Securities)

                                    91307C102
                                    ---------
                                 (CUSIP Number)

                                December 31, 2005
                                -----------------
             (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 on the remainder of this cover page shall not be
  deemed to be "filed" for the 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).



---------------------                                      --------------------
CUSIP No. 91307C102                     13G                Page 2 of 11 Pages
---------------------                                      --------------------

--------------------------------------------------------------------------------
        1  NAME OF REPORTING PERSON
           I.R.S. IDENTIFICATION NO. OF ABOVE PERSON

           S.A.C. Capital Advisors, LLC
--------------------------------------------------------------------------------
        2  CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*
                                                                 (a) /_/
                                                                 (b) /x/
--------------------------------------------------------------------------------
        3  SEC USE ONLY

--------------------------------------------------------------------------------
        4  CITIZENSHIP OR PLACE OF ORGANIZATION

           Delaware
--------------------------------------------------------------------------------
      NUMBER OF          5  SOLE VOTING POWER
        SHARES
     BENEFICIALLY           0
        OWNED         ---------------------------------------------------------
          BY             6  SHARED VOTING POWER
         EACH
      REPORTING             67,600 (see Item 4)
        PERSON        ---------------------------------------------------------
         WITH            7  SOLE DISPOSITIVE POWER

                            0
                      ---------------------------------------------------------
                         8  SHARED DISPOSITIVE POWER

                            67,600 (see Item 4)
--------------------------------------------------------------------------------
        9  AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

           67,600 (see Item 4)
--------------------------------------------------------------------------------
       10  CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES

           / /
--------------------------------------------------------------------------------
       11  PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)

           0.3% (see Item 4)
--------------------------------------------------------------------------------
       12  TYPE OF REPORTING PERSON*

           00
--------------------------------------------------------------------------------
                       *SEE INSTRUCTION BEFORE FILLING OUT

                                  Page 2 of 11




---------------------                                      --------------------
CUSIP No. 91307C102                     13G                Page 3 of 11 Pages
---------------------                                      --------------------

--------------------------------------------------------------------------------
        1  NAME OF REPORTING PERSON
           I.R.S. IDENTIFICATION NO. OF ABOVE PERSON

           S.A.C. Capital Management, LLC
--------------------------------------------------------------------------------
        2  CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*
                                                                     (a) /_/
                                                                     (b) /x/
--------------------------------------------------------------------------------
        3  SEC USE ONLY

--------------------------------------------------------------------------------
        4  CITIZENSHIP OR PLACE OF ORGANIZATION

           Delaware
--------------------------------------------------------------------------------
      NUMBER OF          5  SOLE VOTING POWER
       SHARES
    BENEFICIALLY            0
        OWNED        -----------------------------------------------------------
         BY              6  SHARED VOTING POWER
        EACH
      REPORTING             67,600 (see Item 4)
       PERSON        -----------------------------------------------------------
        WITH             7  SOLE DISPOSITIVE POWER

                            0
                     -----------------------------------------------------------
                         8  SHARED DISPOSITIVE POWER

                            67,600 (see Item 4)
--------------------------------------------------------------------------------
        9  AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

           67,600 (see Item 4)
--------------------------------------------------------------------------------
       10  CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES

           / /
--------------------------------------------------------------------------------
       11  PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)

           0.3% (see Item 4)
--------------------------------------------------------------------------------
       12  TYPE OF REPORTING PERSON*

           00
--------------------------------------------------------------------------------
                       *SEE INSTRUCTION BEFORE FILLING OUT

                                  Page 3 of 11




---------------------                                      --------------------
CUSIP No. 91307C102                     13G                Page 4 of 11 Pages
---------------------                                      --------------------

--------------------------------------------------------------------------------
        1  NAME OF REPORTING PERSON
           I.R.S. IDENTIFICATION NO. OF ABOVE PERSON

           CR Intrinsic Investors, LLC
--------------------------------------------------------------------------------
        2  CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*
                                                                (a) /_/
                                                                (b) /x/
--------------------------------------------------------------------------------
        3  SEC USE ONLY

--------------------------------------------------------------------------------
        4  CITIZENSHIP OR PLACE OF ORGANIZATION

           Delaware
--------------------------------------------------------------------------------
      NUMBER OF          5  SOLE VOTING POWER
       SHARES
    BENEFICIALLY            0
        OWNED        -----------------------------------------------------------
         BY              6  SHARED VOTING POWER
        EACH
      REPORTING             51,000 (see Item 4)
       PERSON        -----------------------------------------------------------
        WITH             7  SOLE DISPOSITIVE POWER

                            0
                     -----------------------------------------------------------
                         8  SHARED DISPOSITIVE POWER

                            51,000 (see Item 4)
--------------------------------------------------------------------------------
        9  AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

           51,000 (see Item 4)
--------------------------------------------------------------------------------
       10  CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES

           / /
--------------------------------------------------------------------------------
       11  PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)

           0.2% (see Item 4)
--------------------------------------------------------------------------------
       12  TYPE OF REPORTING PERSON*

           00
--------------------------------------------------------------------------------
                       *SEE INSTRUCTION BEFORE FILLING OUT

                                  Page 4 of 11




---------------------                                      --------------------
CUSIP No. 91307C102                     13G                Page 5 of 11 Pages
---------------------                                      --------------------

--------------------------------------------------------------------------------
        1  NAME OF REPORTING PERSON
           I.R.S. IDENTIFICATION NO. OF ABOVE PERSON

           Sigma Capital Management, LLC
--------------------------------------------------------------------------------
        2  CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*
                                                                   (a) /_/
                                                                   (b) /x/
--------------------------------------------------------------------------------
        3  SEC USE ONLY

--------------------------------------------------------------------------------
        4  CITIZENSHIP OR PLACE OF ORGANIZATION

           Delaware
--------------------------------------------------------------------------------
      NUMBER OF          5  SOLE VOTING POWER
        SHARES
     BENEFICIALLY           0
        OWNED         ----------------------------------------------------------
          BY             6  SHARED VOTING POWER
         EACH
      REPORTING             0 (see Item 4)
        PERSON        ----------------------------------------------------------
         WITH            7  SOLE DISPOSITIVE POWER

                            0
                      ----------------------------------------------------------
                         8  SHARED DISPOSITIVE POWER

                            0 (see Item 4)
--------------------------------------------------------------------------------
        9  AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

           0 (see Item 4)
--------------------------------------------------------------------------------
       10  CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES

           / /
--------------------------------------------------------------------------------
       11  PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)

           0% (see Item 4)
--------------------------------------------------------------------------------
       12  TYPE OF REPORTING PERSON*

           00
--------------------------------------------------------------------------------
                       *SEE INSTRUCTION BEFORE FILLING OUT

                                  Page 5 of 11




---------------------                                      --------------------
CUSIP No. 91307C102                     13G                Page 6 of 11 Pages
---------------------                                      --------------------

--------------------------------------------------------------------------------
        1  NAME OF REPORTING PERSON
           I.R.S. IDENTIFICATION NO. OF ABOVE PERSON

           Steven A. Cohen
--------------------------------------------------------------------------------
        2  CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*
                                                                 (a) /_/
                                                                 (b) /x/
--------------------------------------------------------------------------------
        3  SEC USE ONLY

--------------------------------------------------------------------------------
        4  CITIZENSHIP OR PLACE OF ORGANIZATION

           United States
--------------------------------------------------------------------------------
      NUMBER OF          5  SOLE VOTING POWER
       SHARES
    BENEFICIALLY            0
        OWNED        -----------------------------------------------------------
         BY              6  SHARED VOTING POWER
        EACH
      REPORTING             118,600 (see Item 4)
       PERSON        -----------------------------------------------------------
        WITH             7  SOLE DISPOSITIVE POWER

                            0
                     -----------------------------------------------------------
                         8  SHARED DISPOSITIVE POWER

                            118,600 (see Item 4)
--------------------------------------------------------------------------------
        9  AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

           118,600 (see Item 4)
--------------------------------------------------------------------------------
       10  CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES

           / /
--------------------------------------------------------------------------------
       11  PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)

           0.5% (see Item 4)
--------------------------------------------------------------------------------
       12  TYPE OF REPORTING PERSON*

           IN
--------------------------------------------------------------------------------
                       *SEE INSTRUCTION BEFORE FILLING OUT

                                  Page 6 of 11



ITEM 1(a)        NAME OF ISSUER:

                 United Therapeutics Corporation

ITEM 1(b)        ADDRESS OF ISSUER'S PRINCIPAL EXECUTIVE OFFICES:

                 1110 Spring Street
                 Silver Spring, ND  20910

ITEMS 2(a)       NAME OF PERSON FILING:

                 This statement is filed by: (i) S.A.C. Capital Advisors, LLC,
                 ("SAC Capital Advisors") with respect to shares of common
                 stock, par value $0.01 per share ("Shares") of the Issuer
                 beneficially owned by S.A.C. Capital Associates, LLC ("SAC
                 Capital Associates"); (ii) S.A.C. Capital Management, LLC,
                 ("SAC Capital Management") with respect to Shares beneficially
                 owned by SAC Capital Associates; (iii) CR Intrinsic Investors,
                 LLC ("CR Intrinsic Investors") with respect to Shares
                 beneficially owned by CR Intrinsic Investments, LLC ("CR
                 Intrinsic Investments"); (iv) Sigma Capital Management, LLC
                 ("Sigma Management") and (iv) Steven A. Cohen with respect to
                 Shares beneficially owned by SAC Capital Advisors, SAC Capital
                 Management, SAC Capital Associates, CR Intrinsic Investors and
                 CR Intrinsic Investments.

ITEM 2(b)        ADDRESS OF PRINCIPAL BUSINESS OFFICE:

                 The address of the principal business office of (i) SAC Capital
                 Advisors, CR Intrinsic Investors and Mr. Cohen is 72 Cummings
                 Point Road, Stamford, Connecticut 06902 and (ii) SAC Capital
                 Management and Sigma Management is 540 Madison Avenue, New
                 York, New York 10022.

ITEM 2(c)        CITIZENSHIP:

                 SAC Capital Advisors, SAC Capital Management, CR Intrinsic
                 Investors and Sigma Management are Delaware limited liability
                 companies. Mr. Cohen is a United States citizen.

ITEM 2(d)        TITLE OF CLASS OF SECURITIES:

                 Common Stock, par value $0.01 per share

                                  Page 7 of 11




ITEM 2(e)       CUSIP NUMBER:

                91307C102

ITEM 3          Not Applicable

ITEM 4          OWNERSHIP:

                The percentages used herein are calculated based upon the Shares
                issued and outstanding as of October 28, 2005 as reported on the
                Issuer's quarterly report on Form 10-Q filed with the Securities
                and Exchange Commission by the Company for the quarterly period
                ended September 30, 2005.

                As of the close of business on December 30, 2005:

                1. S.A.C. Capital Advisors, LLC
                (a) Amount beneficially owned: 67,600
                (b) Percent of class: 0.3%
                (c)(i) Sole power to vote or direct the vote: -0-
                (ii) Shared power to vote or direct the vote: 67,600
                (iii) Sole power to dispose or direct the disposition: -0-
                (iv) Shared power to dispose or direct the disposition: 67,600

                2. S.A.C. Capital Management, LLC
                (a) Amount beneficially owned: 67,600
                (b) Percent of class: 0.3%
                (c)(i) Sole power to vote or direct the vote: -0-
                (ii) Shared power to vote or direct the vote: 67,600
                (iii) Sole power to dispose or direct the disposition: -0-
                (iv) Shared power to dispose or direct the disposition: 67,600

                3. CR Intrinsic Investors, LLC
                (a) Amount beneficially owned: 51,000
                (b) Percent of class: 0.2%
                (c)(i) Sole power to vote or direct the vote: -0-
                (ii) Shared power to vote or direct the vote: 51,000
                (iii) Sole power to dispose or direct the disposition: -0-
                (iv) Shared power to dispose or direct the disposition: 51,000

                4. Sigma Capital Management, LLC
                (a) Amount beneficially owned:  0
                (b) Percent of class: 0 %
                (c)(i) Sole power to vote or direct the vote: 0
                (ii) Shared power to vote or direct the vote: -0-
                (iii) Sole power to dispose or direct the disposition: -0-
                (iv) Shared power to dispose or direct the disposition: 0

                                  Page 8 of 11




                5. Steven A. Cohen
                (a) Amount beneficially owned: 118,600
                (b) Percent of class: 0.5%
                (c)(i) Sole power to vote or direct the vote: -0-
                (ii) Shared power to vote or direct the vote: 118,600
                (iii) Sole power to dispose or direct the disposition: -0-
                (iv) Shared power to dispose or direct the disposition: 118,600

                SAC Capital Advisors, SAC Capital Management, CR Intrinsic
                Investors and Mr. Cohen own directly no Shares. Sigma Management
                owns no shares. Pursuant to investment agreements, each of SAC
                Capital Advisors and SAC Capital Management share all investment
                and voting power with respect to the securities held by SAC
                Capital Associates. Pursuant to an investment management
                agreement, CR Intrinsic Investors has investment and voting
                power with respect to the securities held by CR Intrinsic
                Investments. Mr. Cohen controls each of SAC Capital Advisors,
                SAC Capital Management and CR Intrinsic Investors. CR Intrinsic
                Investments is a wholly owned subsidiary of SAC Capital
                Associates. By reason of the provisions of Rule 13d-3 of the
                Securities Exchange Act of 1934, as amended, each of (i) SAC
                Capital Advisors, SAC Capital Management and Mr. Cohen may be
                deemed to own beneficially 67,600 Shares (constituting
                approximately 0.3% of the Shares outstanding) and (ii) CR
                Intrinsic and Mr. Cohen may be deemed to own beneficially 51,000
                shares (constituting approximately 0.2% of the Shares
                outstanding). Each of SAC Capital Advisors, SAC Capital
                Management, CR Intrinsic Investors and Mr. Cohen disclaim
                beneficial ownership of any of the securities covered by this
                statement. SAC Associates disclaims beneficial ownership of any
                of the securities owned by CR Intrinsic Investments.

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/

ITEM 6          OWNERSHIP OF MORE THAN FIVE PERCENT ON BEHALF OF
                ANOTHER PERSON:

                Not Applicable

                                  Page 9 of 11



ITEM 7          IDENTIFICATION AND CLASSIFICATION OF THE
                SUBSIDIARY WHICH ACQUIRED THE SECURITY BEING
                REPORTED ON BY THE PARENT HOLDING COMPANY:

                Not Applicable

ITEM 8          IDENTIFICATION AND CLASSIFICATION OF MEMBERS
                OF THE GROUP:

                Not Applicable

ITEM 9          NOTICE OF DISSOLUTION OF GROUP:

                Not Applicable

ITEM 10         CERTIFICATION:

         By signing below the signatory certifies that, to the best of his
knowledge and belief, the securities referred to above were not acquired and are
not held for the purpose of or with the effect of changing or influencing the
control of the issuer of the securities and were not acquired and are not held
in connection with or as a participant in any transaction having that purpose or
effect.


                                  Page 10 of 11





                                    SIGNATURE

         After reasonable inquiry and to the best of my knowledge and belief, I
certify that the information set forth in this statement is true, complete and
correct.

Dated:  February 14, 2006

S.A.C. CAPITAL ADVISORS, LLC


By: /s/ Peter Nussbaum
   -----------------------------------------
Name:  Peter Nussbaum
Title: Authorized Person

S.A.C. CAPITAL MANAGEMENT, LLC


By: /s/ Peter Nussbaum
   -----------------------------------------
Name:  Peter Nussbaum
Title: Authorized Person

CR INTRINSIC INVESTORS, LLC


By: /s/ Peter Nussbaum
   -----------------------------------------
Name:  Peter Nussbaum
Title: Authorized Person

SIGMA CAPITAL MANAGEMENT, LLC



By: /s/ Peter Nussbaum
   -----------------------------------------
Name:  Peter Nussbaum
Title: Authorized Person

STEVEN A. COHEN


By: /s/ Peter Nussbaum
   -----------------------------------------
Name:  Peter Nussbaum
Title: Authorized Person


                                  Page 11 of 11