U.S. stocks returned to the red Thursday afternoon, after clawing back from sharp early losses in a day of seesaw trading.

The Dow Jones Industrial Average was down 38 points, or 0.2%, to 16103. The blue-chip index had fallen as many as 206.52 points earlier in the session. The S&P 500 was flat at 1862 points and the Nasdaq Composite Index was down two points at to 4212.

Without admitting to any wrongdoing, Merck & Co., Inc. (NYSE:MRK) Organon unit agrees to pay $31M to settle allegations that it overcharged several states' Medicaid programs. Organon also allegedly offered kickbacks to nursing home pharmacies to support the use of its Remeron antidepressant and promoted it for non-approved indications. Merck acquired Organon as part of its takeover of Schering-Plough in 2009.

OncoGenex Pharmaceuticals Inc. (NASDAQ:OGXI) will report Q3 results on October 30 after the close. The conference call will begin at 1:30 pm PT/4:30 pm ET. Consensus view is a loss of ($0.37) per share on revenues of $4.7M.

Ibio Inc (NYSEMKT: IBIO) is up 52% premarket on robust volume in apparent response to its press release about the applicability of its iBioLaunch technology to the development of antibodies that target Ebola. Overzealous traders appear to be ignoring the long-term nature of the applicability. As previously reported, the company licensed iBioLaunch to would-be ZMapp manufacturer Caliber Biotherapeutics.

Small cap Orasure (NASDAQ:OSUR) is up 13% premarket on average volume in response to a report that FDA Commissioner Dr. Margaret Hamburg visited the company to discuss developing an Ebola screening product based on its home HIV test.

AbbVie Inc (NYSE:ABBV) Board of Directors recommends that shareholders vote against its proposed ₤32.5B takeover of Shire plc (NASDAQ:SHPG) due to the change in tax rules that no longer justifies the transaction. The deal is dead. Shire was down 8% at around noon in London trading after it lost 22% yesterday. This morning in the U.S. it is up 2% premarket on turnover of 128K shares.