SIGA Technologies, Inc. (OTCMKTS:SIGA) today announced that it has commenced a rights offering (the “Rights Offering”) for approximate gross proceeds of $35,000,000. As part of the Rights Offering, each stockholder of the Company is receiving one subscription right for each share of common stock owned as of the previously announced record date of October 12, 2016. Each subscription right will entitle its holder to invest $0.65 towards the purchase of shares of the Company’s common stock at a subscription price equal to the lower of $1.50 or 85% of the volume weighted average price of our shares during market hours on the expiration date of the Rights Offering, as more fully described in the prospectus relating to the Rights Offering.

The Rights Offering is expected to expire at 5:00 pm, New York City time, on November 8, 2016, subject to early termination or extension. Subscription rights that are not exercised prior to the expiration date will expire and have no value.

Through the Rights Offering, the company will issue subscription rights necessary to raise an aggregate of $35,284,792. The Company has entered into an investment agreement, or ‘‘backstop agreement,’’ pursuant to which certain parties have agreed to backstop the Rights Offering by purchasing from the Company, at the subscription price pursuant to a separate private placement, any unsubscribed shares of common stock in the Rights Offering to reach the aggregate amount.

Proceeds from the Rights Offering, in combination with other sources of liquidity, will be used by the Company to satisfy the remaining portion of PharmAthene Inc.’s judgment against the Company.

Stockholders who hold their shares directly will receive a prospectus, together with a letter from the Company describing the Rights Offering, subscription rights certificate and related documentation. Those wishing to exercise their rights should review all materials, properly complete and execute the subscription rights certificate and deliver it and payment in full to the subscription agent:

American Stock Transfer & Trust Company, LLC

6201 15th Avenue

Brooklyn, New York 11219

Attn: Corporate Actions

Tel: (718) 921.8200

Stockholders who hold their shares through a broker, custodian bank or other nominee will be notified of the Rights Offering by such broker, custodian bank or other nominee  and must instruct such broker, custodian bank or other nominee  whether or not to exercise subscription rights on their behalf by completing and returning to such broker, custodian bank or other nominee the form entitled “Beneficial Owner Election Form.”

Stockholders with questions about the rights offering, including questions about subscription procedures and requests for additional copies of this prospectus or other documents, are urged to contact the information agent, D.F. King & Co., Inc., by calling toll free at 1-800-207-2872, or by email at [email protected].

This press release does not constitute an offer to sell or the solicitation of an offer to buy nor will there be any sale of any securities referred to in this press release in any state or jurisdiction in which such offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of such state or jurisdiction. The Rights Offering is being made only by means of a prospectus meeting the requirements of the Securities Act of 1933, as amended.

ABOUT SIGA TECHNOLOGIES, INC.

We are a company specializing in the development and commercialization of solutions for serious unmet medical needs and biothreats. Our lead product is Tecovirimat, TPOXX®, also known as ST-246®, an orally administered antiviral drug that targets orthopoxvirus infections. While TPOXX® is not yet approved as safe and effective by the U.S. Food & Drug Administration, it is a novel small-molecule drug that is being delivered to the Strategic National Stockpile under Project BioShield. In August 2016, the company announced completion of enrollment and dosing in the second and final cohort of healthy subjects for the Phase III clinical study of TPOXX®. For more information about SIGA, please visit SIGA’s web site at www.siga.com.