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): May 14, 2003

SIGA Technologies, Inc.

Delaware                       0-23047                 13-3864870
(State or other jurisdiction     Commission File Number     IRS Employer ID No.
of incorporation)

420 Lexington Avenue, New York, New York 10170
(Address of principal executive offices) (Zip Code)

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

SIGA TECHNOLOGIES, INC.

Form 8-K

TABLE OF CONTENTS

Page

Item 5. Other Events .......................................................   3

Item 7. Pro Forma Financial Statements and Exhibits ........................   4

Signatures ........................................................   5

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Item 5. Other Events

On May 14, 2003, SIGA Technologies, Inc. (the "Company") signed definitive
agreements to acquire substantially all of the assets of Plexus Vaccine Inc. and
assume certain liabilities in exchange for 1,950,000 shares of the Company's
common stock (par value $.0001 per share) and 190,950 of the Company's warrants
and options at an initial exercise price of $1.62 per share. The acquisition was
completed on May 23, 2003.

On June 20, 2003 the Company received gross proceeds of $1,500,000 from a
private placement of 1,250,000 shares of its common stock (par value $.0001) and
625,000 warrants to purchase common stock at an initial exercise price of $2.00
per share. The net proceeds from the private placement were $1,350,000.

Statements contained herein and in future fillings by the Company with the
Securities and Exchange Commission, in the Company's press releases, and in oral
statements made by, or with the approval of, authorized personnel that relate to
the Company's future performance, including, without limitation, statements with
respect to the Company's anticipated results of operations or level of business
for 2003 or for any other future period, are "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 the Company'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 which may cause such
differences include the risk that potential products that appeared promising in
early research or clinical trials to the Company or its collaborators do not
demonstrate efficacy or safety in subsequent pre-clinical or clinical trials,
and the risk that the Company or its collaborators will not obtain appropriate
or necessary governmental approvals to market products tested in such trials.

More detailed information about the Company and the factors discussed above is
set forth in the Company's filings with the Securities and Exchange Commission,
including the Company's Annual Report on Form 10-KSB for the fiscal year ended
December 31, 2002, and in other documents that the Company has filed with the
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.gov.
Those documents may also be obtained free of charge from the Company. The
Company 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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Item 7(a). Pro Forma Financial Statements and Exhibits

(b) Unaudited Pro Forma Balance Sheet (as of May 31, 2003)

The following unaudited pro forma balance sheet is provided for
illustrative purposes only. It illustrates the Company's acquisition of
substantially all the assets of Plexus Vaccine Inc. and the assumption of
certain liabilities in exchange for 1,950,000 shares of the Company's common
stock (par value $.0001) and 190,950 of the Company's options and warrants at an
initial exercise price of $1.62 per share. It also illustrates the sale by the
Company of 1,250,000 shares of its common stock for net proceeds of $1,350,000,
as described in Item 5 of this Form 8-K, as if the asset acquisition and private
placement occurred on May 31, 2003. It does not purport to represent what the
actual results of operations or financial position currently are as a result of
the asset acquisition and private placement or otherwise, and is not necessarily
indicative of the Company's future operating results.

31-May-03         Adjustments       Adjusted as of
31-May-03

ASSETS
Current Assets
Cash & Cash Equiv                  $  729,273        $1,350,000        $2,079,273
Accts. Receivable                      78,335                --            78,335
Prepaid Expense                       136,402                --           136,402
----------------------------------------------
Total Current Assets                     944,010         1,350,000         2,294,010
----------------------------------------------

Fixed Assets
Prop. Plant & Equipment-net            457,600            27,711           485,311
----------------------------------------------

Other Assets                             168,386         4,416,304         4,584,690
----------------------------------------------

TOTAL ASSETS                          $1,569,996        $5,794,015        $7,364,011
----------------------------------------------

LIABILITIES & EQUITY
Current Liabilities
Accounts Payable                   $  578,446        $       --        $  578,446
Accrued Expenses                      112,416           729,142           841,558
Preferred Dividends Payable             7,520                --             7,520
Deferred Revenue                       25,996                --            25,996
Total Current Liabilities                724,378           729,142         1,453,520
----------------------------------------------

Equity
Net Equity                            $  845,618        $5,064,873        $5,910,491
----------------------------------------------

TOTAL LIABILITIES & EQUITY            $1,569,996        $5,794,015        $7,364,011
----------------------------------------------

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(c)   Exhibits. The following documents are filed as exhibits to this report:

Exhibit     Description of Exhibit
-------     ----------------------

99.1        Press Release, dated May 15, 2003, announcing the signing of
definitive agreements in connection with the Company's purchase of
substantially all the assets of Plexus Vaccine Inc.

99.2        Press Release, dated June 24, 2003, announcing the consummation of a
private placement for 1,250,000 shares of the Company's common stock
and warrants to purchase 625,000 shares of the Company's common
stock.

SIGNATURES

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

SIGA TECHNOLOGIES, INC.
(Registrant)

Date: July 10, 2003              By: /s/ Thomas N. Konatich
---------------------------------
Thomas N. Konatich
Chief Financial Officer
(Principal Accounting Officer and
Financial Officer and Vice
President, Finance)

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Exhibit 99.1

SIGA Technologies, Inc. Signs Definitive Agreement to Acquire
Assets of Plexus Vaccine Inc.

To Add Structural Biology, Immunological Bioinformatics Tools to Rapidly
Design Synthetic Vaccines against Dangerous New Pathogens

New York, NY - May 15, 2003 -- SIGA Technologies (NASDAQ: SIGA and FRANKFURT:
SGW 919 473) announced today it has executed a definitive agreement to acquire
substantially all of the assets of San Diego based Plexus Vaccine Inc, including
the equity in Plexus's Danish subsidiary Plexus Denmark ApS. The acquisition is
a strategic move for SIGA to broaden its biowarfare portfolio, and to build its
capability for extremely rapid design and delivery of synthetic vaccines for
dangerous new pathogens. Combined, SIGA and Plexus have the potential for
becoming a significant force in the discovery of vaccine and pharmaceutical
agents to fight emerging pathogens. SIGA plans to incorporate structural biology
capabilities from the Plexus group in California and immunological
bioinformatics expertise from researchers in Denmark, while maintaining its
research and development center in Corvallis, OR. The combined resources should
accelerate the development of new, broadly protective synthetic vaccines against
emerging or maliciously engineered pathogens such as SARS and drug-resistant
biowarfare agents, and lead to vaccines with improved safety profiles for such
pathogens as smallpox. The consummation is subject to customary closing
conditions and is anticipated to close in the second quarter of 2003.

The successful acquisition will allow SIGA to balance its approach to infectious
pathogens, with significant strength in both vaccines and anti-infective drugs.
Dennis E. Hruby, Chief Scientific Officer of SIGA stated: "The addition of
Plexus programs and personnel provides exciting new platform technology for
antigen discovery and rational vaccine design and delivery. We will be able to
expedite testing and delivery of vaccines to the marketplace, with a strong
portfolio in the area of biowarfare defense".

Susan Burgess, PhD, President and CEO of Plexus Vaccine will, upon consummation
of the acquisition, be named as President of SIGA. She states that "in addition
to expertise in the design and delivery of vaccines for cellular immunity and
mucosal immunity, both companies have a targeted interest in counteracting
virulence factors, and in finding novel ways to avoid resistance mechanisms and
genetic variance. We believe this is the future in the fight against dangerous
pathogens. Our increased critical mass may help us accelerate the drive to
commercial products. We intend to have a real impact on world health."

-more-

Plexus Denmark ApS, Plexus's Danish subsidiary to be acquired by SIGA, will work
with research teams headed by Soeren Brunak of the Technical University of
Denmark, and with Soeren Buus of the University of Copenhagen, in immunological
bioinformatics and the computational prediction and experimental validation of
key antigenic elements of pathogens.

SIGA has been utilizing its proprietary vaccine delivery system for smallpox and
chlamydia, while Plexus targets bacterial toxins such as those expressed by
anthrax and plague. These prototype vaccine and drug developments have already
been formulated and are currently entering animal testing, with the expectation
for accelerated product development enabled by the Federal Drug and
Administration legislation regarding Biowarfare products passed June 30, 2002.
SIGA believes that the combination of the two company's technology platforms
should provide SIGA with the ability to attack additional vaccine and drug
targets as well as improving the vaccines and drugs they currently have in
development. This acquisition will provide SIGA new delivery platforms, increase
critical mass of the research team, and accelerate developmental timelines.

About SIGA Technologies, Inc.

SIGA Technologies (www.siga.com) 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. With broad technology platforms in both vaccines and anti-infectives,
SIGA's product development programs emphasize the increasingly serious problem
of drug resistant bacteria. SIGA's vaccine and drugs and anti-infective
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 Wyeth-Ayerst Laboratories (the
pharmaceutical division of American Home Products) and the National Institutes
of Health.

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 and to be acquired, are not guarantees
of future performance. Actual results may differ materially from the
expectations contained in the forward-looking statements. Factors which 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, 2002,
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.gov. 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. For more information about SIGA, please visit the
Company's Web site, www.siga.com.

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Exhibit 99.2

SIGA TECHNOLOGIES COMPLETES PRIVATE PLACEMENT

NEW YORK, June 24, 2003 -- SIGA Technologies, Inc. (NASDAQ: SIGA and FRANKFURT:
SGW 919 473), a biopharmaceuticals company developing products for the
prevention and treatment of serious infectious diseases, including products for
use against biological warfare agents such as smallpox, announced today the
receipt of $1,500,000 from a private placement of an aggregate of 1,250,000
shares of common stock and warrants to purchase 625,000 shares of common stock
at an exercise price of $2.00 per share to a group of private investors.

The offering yielded net proceeds of approximately $1,350,000 to SIGA.

SIGA, which recently completed the acquisition of the assets of Plexus Vaccine
Inc., has expanded its platform technology for antigen discovery and rational
vaccine design and delivery of potential vaccine products to combat agents of
biological terror. SIGA is working on a therapeutic for the treatment of
smallpox for which it received a $1.6 million contract from the U.S. Army at the
end of last year.

About SIGA Technologies, Inc.

SIGA Technologies (www.siga.com) 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. With the recent acquisition of substantially all the assets of Plexus
Vaccine Inc., SIGA will be able to broaden its biowarfare portfolio, and to
build its capability for extremely rapid design and delivery of synthetic
vaccines for dangerous new pathogens. Combined, SIGA and Plexus have 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 Wyeth-Ayerst Laboratories (the pharmaceutical division of
American Home Products) and the National Institutes of Health.

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 and to be acquired, are not guarantees
of future performance. Actual results may differ materially from the
expectations contained in the forward-looking statements. Factors which 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, 2002,
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.gov. 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. For more information about SIGA, please visit the
Company's Web site, www.siga.com.

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