Siga Technologies ( SIGA - Get Report) jumped 18% after the Food and Drug Administration made an emergency allowance for its ST-246 smallpox drug candidate to treat a child who had been accidentally infected with eczema vaccinatum, a possibly fatal disease with similarities to smallpox. Shares of New York-based Siga were rising 83 cents to $5.35.

Research Frontiers ( REFR - Get Report) was up nearly 15% after selling a nonexclusive license to SmartGlass International for its light-control technology used in windows, skylights, doors and other products. Terms weren't disclosed. Shares of the Woodbury, N.Y., company were gaining $1.30 to $10.22.

Footwear retailer Genesco ( GCO - Get Report) was higher after Women's Wear Daily reported that Foot Locker ( FL - Get Report) is readying a bid of between $44 and $46 a share for the Nashville-based company, which might be announced as early as this week. The publication also reported that Foot Locker isn't ruling out a hostile takeover. Genesco shares were adding $3.25, or 8.2%, to $42.85. Foot Locker was up 2 cents to $22.11.

Cleveland Biolabs ( CBLI - Get Report) slid after announcing it sold $30 million worth of shares in a private placement to accredited investors. Shares were off $1, or 9.9%, to $9.19.