UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No.)* UNITED THERAPEUTICS CORPORATION -------------------------------------------------------------------------------- (Name of Issuer) Common Stock, $0.01 Par Value Per Share -------------------------------------------------------------------------------- (Title of Class of Securities) 91307C102 --------- (CUSIP Number) February 23, 2006 ----------------- (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 10 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 --------------------- ----- ---------------------------------------------------- 5 SOLE VOTING POWER 0 NUMBER OF ----- ---------------------------------------------------- SHARES 6 SHARED VOTING POWER BENEFICIALLY OWNED 86,454 (see Item 4) BY EACH ----- ---------------------------------------------------- REPORTING 7 SOLE DISPOSITIVE POWER PERSON WITH 0 ----- ---------------------------------------------------- 8 SHARED DISPOSITIVE POWER 86,454 (see Item 4) ---------- --------------------------------------------------------------------- 9 AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 86,454 (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) 0.4% (see Item 4) ---------- --------------------------------------------------------------------- 12 TYPE OF REPORTING PERSON* 00 ---------- --------------------------------------------------------------------- *SEE INSTRUCTION BEFORE FILLING OUT -------------------------------------- ------------------------------- CUSIP No. 91307C102 13G Page 3 of 10 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 --------------------- ----- ---------------------------------------------------- 5 SOLE VOTING POWER 0 NUMBER OF ----- ---------------------------------------------------- SHARES 6 SHARED VOTING POWER BENEFICIALLY OWNED 86,454 (see Item 4) BY EACH ----- ---------------------------------------------------- REPORTING 7 SOLE DISPOSITIVE POWER PERSON WITH 0 ----- ---------------------------------------------------- 8 SHARED DISPOSITIVE POWER 86,454 (see Item 4) ---------- --------------------------------------------------------------------- 9 AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 86,454 (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) 0.4% (see Item 4) ---------- --------------------------------------------------------------------- 12 TYPE OF REPORTING PERSON* 00 ---------- --------------------------------------------------------------------- *SEE INSTRUCTION BEFORE FILLING OUT -------------------------------------- ------------------------------- CUSIP No. 91307C102 13G Page 4 of 10 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 --------------------- ----- ---------------------------------------------------- 5 SOLE VOTING POWER 0 NUMBER OF ----- ---------------------------------------------------- SHARES 6 SHARED VOTING POWER BENEFICIALLY OWNED 320,000 (see Item 4) BY EACH ----- ---------------------------------------------------- REPORTING 7 SOLE DISPOSITIVE POWER PERSON WITH 0 ----- ---------------------------------------------------- 8 SHARED DISPOSITIVE POWER 320,000 (see Item 4) ---------- --------------------------------------------------------------------- 9 AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 320,000 (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) 1.4% (see Item 4) ---------- --------------------------------------------------------------------- 12 TYPE OF REPORTING PERSON* 00 ---------- --------------------------------------------------------------------- *SEE INSTRUCTION BEFORE FILLING OUT -------------------------------------- ------------------------------- CUSIP No. 91307C102 13G Page 5 of 10 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 --------------------- ----- ---------------------------------------------------- 5 SOLE VOTING POWER 0 NUMBER OF ----- ---------------------------------------------------- SHARES 6 SHARED VOTING POWER BENEFICIALLY OWNED 406,454 (see Item 4) BY EACH ----- ---------------------------------------------------- REPORTING 7 SOLE DISPOSITIVE POWER PERSON WITH 0 ----- ---------------------------------------------------- 8 SHARED DISPOSITIVE POWER 406,454 (see Item 4) ---------- --------------------------------------------------------------------- 9 AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 406,454 (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) 1.7% (see Item 4) ---------- --------------------------------------------------------------------- 12 TYPE OF REPORTING PERSON* IN ---------- --------------------------------------------------------------------- *SEE INSTRUCTION BEFORE FILLING OUT Item 1(a) Name of Issuer: -------------- United Therapeutics Corporation Item 1(b) Address of Issuer's Principal Executive Offices: ----------------------------------------------- 1110 Spring Street Silver Spring, MD 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. MultiQuant Fund, LLC ("SAC MultiQuant"); (ii) S.A.C. Capital Management, LLC, ("SAC Capital Management") with respect to Shares beneficially owned by SAC MultiQuant; (iii) Sigma Capital Management, LLC ("Sigma Management") with respect to Shares beneficially owned by Sigma Capital Associates, LLC ("Sigma Capital Associates") and (iv) Steven A. Cohen with respect to Shares beneficially owned by SAC Capital Advisors, SAC Capital Management, SAC MultiQuant, Sigma Management and Sigma Capital Associates. Item 2(b) Address of Principal Business Office: ------------------------------------- The address of the principal business office of (i) SAC Capital Advisors, 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 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 Item 2(e) CUSIP Number: ------------- 91307C102 Item 3 Not Applicable Page 6 of 10 Item 4 Ownership: ---------- The percentages used herein are calculated based upon the Shares issued and outstanding as of February 21, 2006 as reported on the Issuer's annual report on Form 10-K filed with the Securities and Exchange Commission by the Company for the fiscal year ended December 31, 2005. As of the close of business on March 2, 2006: 1. S.A.C. Capital Advisors, LLC (a) Amount beneficially owned: 86,454 (b) Percent of class: 0.4% (c)(i) Sole power to vote or direct the vote: -0- (ii) Shared power to vote or direct the vote: 86,454 (iii) Sole power to dispose or direct the disposition: -0- (iv) Shared power to dispose or direct the disposition: 86,454 2. S.A.C. Capital Management, LLC (a) Amount beneficially owned: 86,454 (b) Percent of class: 0.4% (c)(i) Sole power to vote or direct the vote: -0- (ii) Shared power to vote or direct the vote: 86,454 (iii) Sole power to dispose or direct the disposition: -0- (iv) Shared power to dispose or direct the disposition: 86,454 3. Sigma Capital Management, LLC (a) Amount beneficially owned: 320,000 (b) Percent of class: 1.4% (c)(i) Sole power to vote or direct the vote: -0- (ii) Shared power to vote or direct the vote: 320,000 (iii) Sole power to dispose or direct the disposition: -0- (iv) Shared power to dispose or direct the disposition: 320,000 4. Steven A. Cohen (a) Amount beneficially owned: 406,454 (b) Percent of class: 1.7% (c)(i) Sole power to vote or direct the vote: -0- (ii) Shared power to vote or direct the vote: 406,454 (iii) Sole power to dispose or direct the disposition: -0- (iv) Shared power to dispose or direct the disposition: 406,454 Page 7 of 10 SAC Capital Advisors, SAC Capital Management, Sigma Management and Mr. Cohen own directly 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 MultiQuant. Pursuant to an investment management agreement, Sigma Management maintains investment and voting power with respect to the securities held by Sigma Capital Associates. Mr. Cohen controls each of SAC Capital Advisors, SAC Capital Management and Sigma Management. 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 86,454 Shares (constituting approximately 0.4% of the Shares outstanding) and (ii) Sigma Management and Mr. Cohen may be deemed to own beneficially 320,000 shares (constituting approximately 1.4% of the Shares outstanding). Each of SAC Capital Advisors, SAC Capital Management, Sigma Management and Mr. Cohen disclaim beneficial ownership of any of the securities covered by this statement. 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 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 Page 8 of 10 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 9 of 10 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: March 3, 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 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 10 of 10