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


                                    FORM 8-K

                             CURRENT REPORT PURSUANT
                         TO SECTION 13 OR 15(D) OF THE
                         SECURITIES EXCHANGE ACT OF 1934


       Date of report (Date of earliest event reported): January 30, 2004

                                   ----------


                             SIGA Technologies, Inc.
                             -----------------------
               (Exact Name of Registrant as Specified in Charter)


           Delaware                     0-23047                13-3864870
           --------                     -------                ----------

 (State or other Jurisdiction of     (Commission File       (I.R.S. Employer
  Incorporation or Organization)         Number)          Identification Number)



           420 Lexington Avenue, Suite 601
                New York, New York                                10170
         -----------------------------------                    ---------
       (Address of Principal Executive Offices)                 (Zip Code)


                                 (212) 672-9100
                                 --------------
              (Registrant's telephone number, including area code)



ITEM 7. Financial Statements, Pro Forma Financial Information and Exhibits


(b)     Pro Forma Financial Information.

        Introduction to Unaudited Pro Forma Financial Statements.

        Unaudited Pro Forma Statement of Operations for the nine months ended
        September 30, 2003.

        Unaudited Pro Forma Statement of Operations for the year ended December
        31, 2002.

        Notes to Unaudited Pro Forma Financial Statements.


                    UNAUDITED PRO FORMA FINANCIAL STATEMENTS

On May 23, 2003, SIGA Technologies, Inc. ("SIGA") acquired substantially all of
the assets of Plexus Vaccine Inc. ("Plexus") and assumed certain liabilities in
exchange for 1,950,000 shares of SIGA's common stock and 190,950 of SIGA's
options and warrants at an exercise price of $1.62 per share.

The following unaudited pro forma financial statements give effect to the asset
purchase agreement between SIGA and Plexus. The unaudited pro forma statements
of operations are based on the individual statements of operations of SIGA and
Plexus appearing in SIGA's most recent annual and quarterly reports and in the
Current Report on Form 8-K/A of SIGA dated July 22, 2003, respectively, and
combine the results of operations of SIGA and Plexus for the nine months ended
September 30, 2003 and for the year ended December 31, 2002 as if the
transaction occurred on January 1, 2002. For the nine months ended September 30,
2003, the historical Plexus statement of operation is for the period January 1,
2003 through May 23, 2003, as the entities were combined as of that date.

The unaudited pro forma information is presented for illustrative purposes only
and is not necessarily indicative of the operating results that would have been
achieved if the acquisition had been consummated as of the beginning of the
periods presented, nor are they necessarily indicative of future operating
results of SIGA. A preliminary allocation of the purchase price has been made to
certain identifiable tangible and intangible assets based on information
available to the management of SIGA at the date of the preparation of the
accompanying pro forma financial statements. The pro forma financial information
does not give effect to any costs savings or incremental costs, which may result
from the integration of SIGA and Plexus operations.


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                                             SIGA Technologies, Inc. and Subsidiaries
                                            Unaudited Pro Forma Statement of Operations
                                            For the Nine Months Ended September 30, 2003

                                                               Historical                                    Pro Forma
                                                           --------------------------------------------------------------------
                                                                               For the period
                                                              For the nine       January 1,
                                                              months ended      2003 through
                                                            September 30, 2003  May 23, 2003
                                                                SIGA (1)         Plexus (2)      Adjustments (3)      Combined
                                                            ------------------ --------------    ---------------    ------------
Revenues:

                                                                                                        
  Grants and research and development contracts               $    625,016      $     94,782      $       --        $    719,798
                                                              ------------      ------------      -----------       ------------
       Total revenues                                              625,016            94,782              --             719,798
                                                              ------------      ------------      -----------       ------------
Operating expenses:
  General and administrative                                     1,993,007           907,308        84,167 (A)         2,984,482
  Research and development                                       2,121,154           243,417       179,506 (B)         2,544,077
  Patent preparation fees                                          187,109              --                --             187,109
                                                              ------------      ------------      -----------       ------------
       Total operating expenses                                  4,301,270         1,150,725           263,673         5,715,668
                                                              ------------      ------------      -----------       ------------

       Operating loss                                           (3,676,254)       (1,055,943)         (263,673)       (4,995,870)

  Interest income / (expense), net                                  13,048          (949,129)             --            (936,081)
                                                              ------------      ------------      -----------       ------------

  Net loss applicable to common shareholders                  $ (3,663,206)     $ (2,005,072)     $   (263,673)     $ (5,931,951)
                                                              ============      ============      ============      ============
  Weighted average number of common shares
    outstanding                                                 14,769,960                        1,021,429 (C)       15,791,389
                                                              ============                                          ============
  Weighted average common shares outstanding used
    for basic and diluted loss per share                      $      (0.25)                                         $      (0.38)
                                                              ============                                          ============


See notes to Unaudited Pro Forma Financial Statements.


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                                        SIGA Technologies, Inc. and Subsidiaries
                                      Unaudited Pro Forma Statement of Operations
                                         For the Year Ended December 31, 2002


                                                                        Historical                        Pro Forma
                                                              -----------------------------    ----------------------------
                                                                 SIGA (1)        Plexus (2)    Adjustments (3)     Combined
                                                              ------------     ------------    --------------    ----------
                                                                                                     
Revenues:
  Research and development contracts                          $    344,450     $    172,378     $       --       $    516,828
                                                              ------------     ------------     ------------     ------------
      Total revenues                                               344,450          172,378             --            516,828
                                                              ------------     ------------     ------------     ------------

Operating expenses:
  General and administrative                                     1,838,470          573,836          202,000 (A)    2,614,306
  Reseach and development                                        1,766,368          937,593          430,814 (B)    3,134,775
  Patent preparation fees                                          104,700             --               --            104,700
                                                              ------------     ------------     ------------     ------------
      Total operating expenses                                   3,709,538        1,511,429          632,814        5,853,781
                                                              ------------     ------------     ------------     ------------

      Operating loss                                            (3,365,088)      (1,339,051)        (632,814)      (5,336,953)

  Interest income / (expense), net                                  34,061          (66,638)            --            (32,577)
                                                              ------------     ------------     ------------     ------------

  Net loss                                                      (3,331,027)      (1,405,689)        (632,814)      (5,369,530)

  Deemed dividend related to beneficial conversion feature          29,200             --               --             29,200
                                                              ------------     ------------     ------------     ------------

  Net loss applicable to common stockholders                  $ (3,360,227)    $ (1,405,689)    $   (632,814)    $ (5,398,730)
                                                              ============     ============     ============     ============
  Basic and diluted loss per share                            $      (0.32)                                      $      (0.44)
                                                              ============                                       ============
  Weighted average common shares outstanding used
    for basic and diluted loss per share                        10,450,529                         1,950,000 (C)   12,400,529
                                                              ============                                       ============

See notes to Unaudited Pro Forma Financial Statements.



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              NOTES TO UNAUDITED PRO FORMA FINANCIAL STATEMENTS

1.   These columns reflect the historical results of operations of SIGA for the
     nine month period ended September 30, 2003 and for the year ended December
     31, 2002, respectively.

2.   These columns reflect the historical results of operations of Plexus for
     the period January 1, 2003 through May 23, 2003 and the year ended December
     31, 2002, respectively.

3.   The preliminary allocation of the purchase price of approximately
     $4,070,903 is as follows:

            Net liabilities assumed     $ (466,431)
            Acquired technology          2,191,000
            Contracts and grants           741,000
            Covenant not to compete        707,000
            Goodwill                       898,334
                                        ----------
                                        $4,070,903
                                        ==========

The following are the descriptions of the intangible assets acquired from Plexus
and the methodologies in valuing each intangible asset.

Acquired Technology

The acquired technology from Plexus is comprised of a combination of technology
and know-how of computational platforms and in vitro and in vivo testing
capabilities for rational design of vaccines. The acquired technology includes
one patent, two patent applications, and six pending patents supporting such
technologies, as well as certain unpatented technology. As such, the acquired
technology arises from contractual or legal rights, or can be transferred,
licensed, rented or exchanged in combination with these patents, and therefore
meets the separable criteria presented in paragraph 39 of SFAS 141.

The acquired technology was valued utilizing an income approach via a relief
from royalty methodology. This methodology is based upon the premise that the
recognition of intellectual assets by potential customers and competitors is a
valuable asset to the owner. The premise behind the valuation of these assets is
that a buyer would be willing to pay a royalty for the right to use an
established technology. Accordingly, this methodology values the technology via
the relief from the royalty that a willing buyer would typically pay. This
methodology is comprised of two elements, the determination of an appropriate
royalty rate and the conversion of royalty savings into value. Based on a review
of royalty rates paid in third-party licensing agreements, a royalty rate of
3.0% of revenue was used over an estimated useful life of ten years. Royalty
"savings" were then discounted to a present value utilizing a discount rate of
28.5%.


                                       5



Contracts and Grants

SIGA acquired several contracts and grants with various institutions, the terms
of which range from two and a half to four and a half years, and are expected to
generate revenue in future periods. The contracts and grants arise from
contractual rights and were recognized pursuant to paragraph 39 of SFAS 141.

The contracts and grants were valued utilizing an income approach known as the
excess earnings methodology, whereby excess earnings are computed as the
earnings remaining after deducting for the market rates of return on the
estimated value of contributory assets including working capital, tangible and
intangible assets. The excess earnings are thereby calculated for each year of a
multiyear projection period. The primary components of this methodology consist
of the determination of excess earnings and an appropriate rate of return. The
earnings were based on projected after-tax profits over the estimated term (two
and a half to four and a half years) discounted at a rate of 26.0%.

Covenant Not to Compete

As part of the asset purchase, SIGA entered into a three and a half year
non-competition agreement with the president of Plexus. The covenant not to
compete arises from contractual rights and was recognized pursuant to paragraph
39 of SFAS 141.

The covenant not to compete was valued utilizing an income approach via the
discounted cash flow methodology, which is based upon converting expected lost
earnings over the three and a half year term to present value. This methodology
calculates the present value of potential lost earnings, by giving values to
five discrete scenarios as to the timing of when the president would compete had
there not been an agreement in place. Each scenario was then weighted, based on
the probability of each scenario occurring, to arrive at the intangible asset
value.

Under this approach, lost earnings before interest and taxes was estimated for
each scenario. These earnings were then tax affected and converted into value
utilizing a discount rate of 26.0%.

The following adjustments were made to the statement of operations for the nine
months ended September 30, 2003 and for the year ended December 31, 2002 to give
effect to the transaction:

     A)   Amortization of the covenant not to compete based on the contractual
          life of the agreement.

     B)   Amortization of acquired technology and contracts and grants over the
          estimated useful life.

     C)   Weighted average shares increase based on common stock issued.


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                                   SIGNATURES


            Pursuant to the requirements of the Securities Exchange Act of 1934,
the registrant has duly caused this report to be signed on its behalf by the
undersigned hereunto duly authorized.

                                    SIGA TECHNOLOGIES, INC.


                                    By: /s/ Thomas N. Konatich
                                       ----------------------------
                                       Thomas N. Konatich
                                       Acting Chief Executive Officer and
                                       Chief Financial Officer

Date:  January 30, 2004



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