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): June 9, 2004

                                   ----------


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

                                    Delaware
                                    --------
                         (State or other Jurisdiction of
                         Incorporation or Organization)

            0-23047                                           13-3864870
            -------                                           ----------
        (Commission File                                   (I.R.S. Employer
            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 5. Other Events and Required FD Disclosure. On June 9, 2004, SIGA Technologies, Inc., a Delaware corporation ("SIGA"), issued a press release pursuant to which SIGA announced the signing of an Asset Purchase Agreement to acquire certain antiviral programs targeting potential agents of biological warfare from ViroPharma Incorporated (VPHM) for a purchase price of $1 million in cash and 1 million shares of SIGA common stock. SIGA will purchase lead compounds, assays and scientific know-how related to development of antiviral drugs, including those targeting smallpox and hemorrhagic fever viruses such as the Ebola virus. The research programs being acquired are currently the subject of grants from the National Institutes of Health (NIH). The closing of the acquisition is subject to customary closing conditions, including obtaining approval of the transfer of the grants. For a description of the events reported pursuant to this Form 8-K, reference is made to the press release issued by SIGA on June 9, 2004, the text of which is attached hereto as Exhibit 99.1. ITEM 7. Financial Statements, Pro Forma Financial Information and Exhibits (c) Exhibits Exhibit No. Description ----------- ----------- 99.1 Press Release dated June 9, 2004. 2

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: June 9, 2004 3

EXHIBIT INDEX Exhibit Number Description - -------------- ----------- 99.1 Press Release dated June 9, 2004. 4

                                                                    EXHIBIT 99.1
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[SIGA LOGO]

Contact:                                              Investor Contact:
Thomas N. Konatich                                    Dianne Will
SIGA Technologies, Inc.                               Willstar Consultants, Inc.
CFO & Acting CEO                                      (518) 398-6222
(212) 672-9100                                        dwill@willstar.net
                                                      ------------------


     SIGA announces AGREEMENT WITH VIROPHARMA TO PURCHASE BIODEFENSE ASSETS

New York, June 9, 2004 -- SIGA Technologies, Inc. (NASDAQ: SIGA) and (FRANKFURT:
SGW 919 473) today announced the signing of an Asset Purchase Agreement to
acquire certain antiviral programs targeting potential agents of biological
warfare from ViroPharma Incorporated (VPHM) for a purchase price of $1 million
in cash and 1 million shares of SIGA common stock. SIGA will purchase lead
compounds, assays and scientific know-how related to development of antiviral
drugs, including those targeting smallpox and hemorrhagic fever viruses such as
the Ebola virus. The research programs being acquired are currently the subject
of grants from the National Institutes of Health (NIH). The closing of the
acquisition is subject to customary closing conditions, including obtaining
approval of the transfer of the grants. "We are very pleased to add these
exciting programs to our biodefense research and development portfolio.
Effective protection of our population will require multiple drugs against
multiple pathogens, and these additional product opportunities will provide SIGA
with the means to contribute to this process," remarked Dr. Dennis E. Hruby,
SIGA's Chief Scientific Officer.

About SIGA Technologies, Inc.
SIGA Technologies is applying bacterial genomics in the design and development
of novel products for the prevention and treatment of serious infectious
diseases, with an emphasis on products for biological warfare defense. SIGA has
the potential of becoming a significant force in the discovery of vaccine and
pharmaceutical agents to fight emerging pathogens. SIGA's product development
programs emphasize the increasingly serious problem of drug resistant bacteria
and emerging pathogens.

SIGA's vaccine and drug platforms are based on its pioneering research into the
structure, function and processing of bacterial surface proteins. SIGA is
leveraging these platforms through multiple strategic partners, including the
National Institutes of Health and TransTech Pharma. For more information about
SIGA, please visit SIGA's Web site at www.siga.com.

This news release contains certain "forward-looking statements" within the
meaning of the Private Securities Litigation Reform Act of 1995. Such
statements, including statements regarding the efficacy and intended utilization
of SIGA's technologies under development, are not guarantees of future
performance. Actual results may differ materially from the expectations
contained in the forward-looking statements. Factors that may cause such
differences include the risk that potential products that appeared promising in
early research or clinical trials to SIGA or its collaborators do not
demonstrate efficacy or safety in subsequent pre-clinical or clinical trials,
and the risk that SIGA or its collaborators will not obtain appropriate or
necessary governmental approvals to market products tested in such trials. More
detailed information about SIGA and the factors discussed above is set forth in
SIGA's filings with the Securities and Exchange Commission, including SIGA's
Annual Report on Form 10-K for the fiscal year ended December 31, 2003, and in
other documents that SIGA has filed with the U.S. Securities and Exchange
Commission. Investors and security holders are urged to read those documents
free of charge at the Commission's web site at www.sec.com. Those documents may
also be obtained free of charge from SIGA. SIGA does not undertake to publicly
update or revise its forward-looking statements as a result of new information,
future events or otherwise.
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