SC 13G

                             SECURITIES AND EXCHANGE COMMISSION
                                  Washington, D.C.  20549

                                        SCHEDULE 13G

                         Under the Securities Exchange Act of 1934


                                    GENAERA CORPORATION
                                      (Name of Issuer)

                                       Common Stock
                               (Title of Class of Securities)

                                         36867G100
                                      (CUSIP Number)

                                     January 21, 2004
                  (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
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. 36867G100

1.  Name of Reporting Person:

     HBK Investments L.P.

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: less than 5% of Issuer's outstanding
Number of         shares of the Class (1)(2)(3)
Shares
Beneficially  6.  Shared Voting Power:  0
Owned By
Each
Reporting     7.  Sole Dispositive Power: less than 5% of Issuer's outstanding
Person            shares of the Class (1)(2)(3)
With
              8.  Shared Dispositive Power:  0

9.    Aggregate Amount Beneficially Owned by Each Reporting Person:

       Less than 5% of Issuer's outstanding shares of the Class (1)(2)(3)

10.  Check Box if the Aggregate Amount in Row (9) Excludes Certain Shares:
                                                            /  /

11.  Percent of Class Represented by Amount in Row (9): Less than 5% of
Issuer's outstanding shares (2)

12.  Type of Reporting Person: PN

- --------------
(1)  Consists of 4,678,222 shares of Common Stock of the Issuer and 935,644
     shares of Common Stock of the Issuer issuable upon exercise of warrants
     (the "Shares") owned by Heimdall Investments Ltd. ("Heimdall").  As of the
     date of the event that required filing of this Statement, HBK Investments
     L.P. ("Investments") had sole voting power and sole dispositive power over
     the Shares pursuant to an Investment Management Agreement with Heimdall.
     Accordingly, Heimdall has and had no beneficial ownership of such
     Shares.

(2)  As of the date of the event that required filing of this statement,
     Investments had sole voting power and sole dispositive power over the
     Shares.  Such ownership represented approximately 9.9% of the outstanding
     shares of the Issuer's Common Stock (the "Class") as of the date
     of the event that required filing of this Statement.  Investments now has
     sole voting and dispositive power over less than 5% of the outstanding
     shares of the Class.



(3)  Investments' power is exercised by its general partner, HBK Partners II
     L.P., whose general partner is HBK Management L.L.C.




Item 1(a).     Name of Issuer.

    The name of the issuer is Genaera Corporation (the "Issuer").

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

    The principal executive offices of the Issuer are located at 5110 Campus
Drive, Plymouth Meeting, Pennsylvania 19462.

Item 2(a).    Names of Persons Filing.

    Pursuant to Rules 13d-1(k)(1)-(2) of Regulation 13D-G of the General Rules
and Regulations under the Securities Exchange Act of 1934, as amended (the
"Act"), this Schedule 13G Statement is hereby filed by HBK Investments L.P.,
a Delaware limited partnership (the "Reporting Person"). Additionally,
information is included herein with respect to the following persons
(collectively, the "Controlling Persons"): HBK Partners II L.P., a Delaware
limited partnership ("Partners II"), HBK Management L.L.C., a Delaware limited
liability company ("Management") and Kenneth M. Hirsh, Laurence H. Lebowitz,
William E. Rose, Richard L. Booth, David C. Haley and Jamiel A. Akhtar, members
of Management, who may control Management ("Managers").  The Reporting Person
and the Controlling Persons are sometimes hereinafter collectively referred to
as the "Item 2 Persons."

Item 2(b).    Address of Principal Business Office, or if None, Residence.

    The principal business office for each of the Item 2 Persons is 300
Crescent Court, Suite 700, Dallas, Texas 75201.

Item 2(c).    Citizenship.

     All of the natural persons listed in Item 2(a) are citizens of the United
States of America.

Item 2(d).    Title of Class of Securities.

    This statement relates to the Common Stock of the Issuer.

Item 2(e).    CUSIP Number.

    The CUSIP number of the Shares is 36867G100.

Item 3.  Filing Pursuant to Rules 13d-1(b) or 13d-2(b).

     If this statement is filed pursuant to Sections 240.13d-1(b) or
240.13d-2(b) or (c), check whether the person filing is a:

    (a) / /  Broker or dealer registered under section 15 of the Act
(15 U.S.C. 78o);

    (b) / /  Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c);

    (c) / /  Insurance company as defined in section 3(a)(19) of the Act
(15 U.S.C. 78c);




    (d) / / Investment company registered under section 8 of the Investment
Company Act of 1940 (15 U.S.C. 80a-8);

    (e) / /  An investment adviser in accordance with section 240.13d-1(b)(1)
(ii)(E);

    (f) / /  An employee benefit plan or endowment fund in accordance with
section 240.13d-1(b)(1)(ii)(F);

    (g) / /  A parent holding company or control person in accordance with
section 240.13d-1(b)(1)(ii)(G);

    (h) / /  A savings associations as defined in Section 3(b) of the Federal
Deposit Insurance Act (12 U.S.C. 1813);

    (i) / /  A church plan that is excluded from the definition of an
investment company under section 3(c)(14) of the Investment Company Act of 1940
(15 U.S.C. 80a-3);

    (j) / /  Group, in accordance with section 240.13d-1(b)(1)(ii)(J).

    If this statement is filed pursuant to section 240.13d-1(c), check this
box /X/.

Item 4.  Ownership.

    (a) - (b)

    Reporting Persons

     Pursuant to an Investment Management Agreement, Investments may, pursuant
to Rule 13d-3(a), be deemed to be the beneficial owner of the Shares.

    Controlling Persons

    Because of its position as the sole general partner of Investments,
Partners II may be deemed to be the beneficial owner of the Shares.

    Each of (1) Management, as sole general partner of Partners II, and (2) the
Managers, as the controlling persons of Management may, pursuant to Rule 13d-3
of the Act, be deemed to be the beneficial owner of the Shares.

    The Persons listed in Item 2(a) expressly declare that the filing of this
statement on Schedule 13G shall not be construed as an admission that they are,
for the purpose of Section 13(d) or 13(g) of the Act, the beneficial owners of
any securities covered by this statement.

    (c)

    Reporting Persons

    Pursuant to an Investment Management Agreement with Heimdall, and acting
through its general partner, Partners II, Investments has the sole power to
vote or direct the vote and to dispose or to direct the disposition of the
Shares.




    Controlling Persons

    Acting through its general partner, Management, and in its capacity as the
general partner of Investments, Partners II has the sole power to vote or to
direct the vote and to dispose or to direct the disposition of the Shares.

    In its capacity as the general partner of Partners II, Management has the
sole power to vote or to direct the vote and to dispose or to direct the
disposition of the Shares.


    Managers

     In their capacity as controlling persons of Management, the Managers have
the sole power to vote or to direct the vote and to dispose or to direct the
disposition of the Shares.

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

    As of the filing date, Investments does not own 5% or more of the Class.

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 I certify that, to the best of my 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.

    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:    January 30, 2004

                                           HBK INVESTMENTS L.P.


                                           By:  /s/ Kevin O'Neal
                                                Kevin O'Neal
                                                Authorized Signatory (1)

(1)  An Authorization Certificate authorizing Kevin O'Neal to act on behalf
     of HBK Investments L.P. is being filed herewith.

EX-1

                            HBK INVESTMENTS L.P.


                         AUTHORIZATION CERTIFICATE

     Reference is made to that certain Second Amended and Restated Limited
Partnership Agreement of HBK INVESTMENTS L.P., a Delaware limited partnership
(the "Partnership"), dated as of January 1, 1997 (the "Agreement").  All
capitalized terms which are not defined herein shall have the meanings set
forth in the Agreement.

     The undersigned, being the sole General Partner in the Partnership,
pursuant to Section 7.1 of the Agreement, does hereby authorize Kenneth M.
Hirsh, Laurence H. Lebowitz, William E. Rose, Richard L. Booth, Jr., David C.
Haley, Jamiel A. Akhtar, Kevin O'Neal and Benjamin Heller, to act for and on
behalf of the Partnership and to execute such documents, make such filings,
seek such approvals and take such actions as may be necessary or advisable in
order to carry out the purposes of the Partnership.

     IN WITNESS WHEREOF, the undersigned has executed this Authorization
Certificate as of the 30th day of September, 2003.


                                      GENERAL PARTNER

                                      HBK Partners II L.P.

                                      By:  HBK Management LLC,
                                           its sole general partner

                                           By:  /s/ David C. Haley
                                                David C. Haley
                                                Member, Authorized Signatory