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


                                  SCHEDULE 13G

                    Under the Securities Exchange Act of 1934
                               (Amendment No. 2)*

                                  Nuvelo, Inc.
--------------------------------------------------------------------------------
                                (Name of Issuer)

                                  Common Stock
--------------------------------------------------------------------------------
                         (Title of Class of Securities)

                                    67072M103
                                    ---------
                                 (CUSIP Number)

                                  April 3, 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. 67072M103                         13G    Page  2  of   8 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
BY EACH REPORTING           535,000 (see Item 4)
PERSON WITH          ------ ----------------------------------------------------
                         7  SOLE DISPOSITIVE POWER

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

                            535,000 (see Item 4)
---------- ---------------------------------------------------------------------
        9  AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

           535,000 (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)

           1.0% (see Item 4)
---------- ---------------------------------------------------------------------
       12  TYPE OF REPORTING PERSON*

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

                                 Page 2 of 8



-----------------------------------------          -----------------------------
CUSIP No. 67072M103                         13G    Page  3  of   8 Pages
-----------------------------------------          -----------------------------

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

           Sigma Capital Associates, 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

           Anguilla, British West Indies
-------------------- ------ ----------------------------------------------------
                         5  SOLE VOTING POWER

                            0
                     ------ ----------------------------------------------------
NUMBER OF SHARES         6  SHARED VOTING POWER
BENEFICIALLY OWNED
BY EACH REPORTING           535,000 (see Item 4)
PERSON WITH          ------ ----------------------------------------------------
                         7  SOLE DISPOSITIVE POWER

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

                            535,000 (see Item 4)
---------- ---------------------------------------------------------------------
        9  AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

           535,000 (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)

           1.0% (see Item 4)
---------- ---------------------------------------------------------------------
       12  TYPE OF REPORTING PERSON*

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

                                 Page 3 of 8



-----------------------------------------          -----------------------------
CUSIP No. 67072M103                         13G    Page  4  of   8 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
BY EACH REPORTING           535,000 (see Item 4)
PERSON WITH          ------ ----------------------------------------------------
                         7  SOLE DISPOSITIVE POWER

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

                            535,000 (see Item 4)
---------- ---------------------------------------------------------------------
        9  AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

           535,000 (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)

           1.0% (see Item 4)
---------- ---------------------------------------------------------------------
       12  TYPE OF REPORTING PERSON*

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

                                 Page 4 of 8




Item 1(a)           Name of Issuer:
                    --------------

                    Nuvelo, Inc.

Item 1(b)           Address of Issuer's Principal Executive Offices:
                    -----------------------------------------------

                    201 Industrial Road, Suite 310
                    San Carlos, CA 94070

Items 2(a)          Name of Person Filing:

                    This statement is filed by: (i) Sigma Capital Management,
                    LLC ("Sigma Capital Management") with respect to Shares
                    beneficially owned by Sigma Capital Associates, LLC ("Sigma
                    Capital Associates"); (ii) Sigma Capital Associates with
                    respect to Shares beneficially owned by it; and (iii)
                    Steven A. Cohen with respect to Shares beneficially owned
                    by Sigma Capital Management and Sigma Capital Associates.

Item 2(b)           Address of Principal Business Office:
                    -------------------------------------

                    The address of the principal business office of Mr. Cohen is
                    72 Cummings Point Road, Stamford, Connecticut 06902, (ii)
                    Sigma Capital Management is 540 Madison Avenue, New York,
                    New York 10022, and (iii) Sigma Capital Associates is P.O.
                    Box 58, Victoria House, The Valley, Anguilla, British West
                    Indies.

Item 2(c)           Citizenship:
                    ------------

                    Sigma Capital Management is a Delaware limited liability
                    company. Sigma Capital Associates is an Anguillan limited
                    liability company. Mr. Cohen is a United States citizen.

Item 2(d)           Title of Class of Securities:
                    -----------------------------

                    Common Stock

Item 2(e)           CUSIP Number:
                    -------------

                    67072M103

Item 3              Not Applicable

Item 4              Ownership:
                    ----------

                    The percentages used herein are calculated based upon the
                    Shares issued and outstanding as of February 28, 2006 as
                    reported on the

                                  Page 5 of 8



                    Issuer's annual report on Form 10-K filed with the
                    Securities and Exchange Commission by the Issuer for the
                    fiscal year ended December 31, 2005.

                    As of the close of business on April 10, 2006:

                    1. Sigma Capital Management, LLC
                    (a)    Amount beneficially owned: 535,000
                    (b)    Percent of class: 1.0%
                    (c)(i) Sole power to vote or direct the vote: -0-
                    (ii)   Shared power to vote or direct the vote: 535,000
                    (iii)  Sole power to dispose or direct the disposition:  -0-
                    (iv)   Shared power to dispose or direct the disposition:
                           535,000

                    2. Sigma Capital Associates, LLC
                    (a)    Amount beneficially owned: 535,000
                    (b)    Percent of class: 1.0%
                    (c)(i) Sole power to vote or direct the vote: -0-
                    (ii)   Shared power to vote or direct the vote: 535,000
                    (iii)  Sole power to dispose or direct the disposition:  -0-
                    (iv)   Shared power to dispose or direct the disposition:
                           535,000

                    3. Steven A. Cohen
                    (a)    Amount beneficially owned: 535,000
                    (b)    Percent of class: 1.0%
                    (c)(i) Sole power to vote or direct the vote: -0-
                    (ii)   Shared power to vote or direct the vote: 535,000
                    (iii)  Sole power to dispose or direct the disposition:  -0-
                    (iv)   Shared power to dispose or direct the disposition:
                           535,000

                    Sigma Capital Management and Mr. Cohen own directly no
                    Shares. Pursuant to an investment management agreement,
                    Sigma Capital Management maintains investment and voting
                    power with respect to the securities held by Sigma Capital
                    Associates. Mr. Cohen controls Sigma Capital Management. By
                    reason of the provisions of Rule 13d-3 of the Securities
                    Exchange Act of 1934, as amended, Sigma Capital Management
                    and Mr. Cohen may be deemed to own beneficially 535,000
                    Shares (constituting approximately 1.0% of the Shares
                    outstanding). Each of Sigma Capital Management and Mr. Cohen
                    disclaim beneficial ownership of any of the securities
                    covered by this statement.

                                  Page 6 of 8





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

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 7 of 8




                                    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:   April 11, 2006


SIGMA CAPITAL MANAGEMENT, LLC


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


SIGMA CAPITAL ASSOCIATES, 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 8 of 8