U.S. stocks closed flat despite a spate of merger news; 10-year interest rates were unchanged at 4.59%, but energy prices traded sharply lower. The Dow Jones Industrials slipped 6 points and the CBOE Volatility Index (VIX) jumped 5% to 10.59. In M&A (Merger & Acquisition) news, Biomet (BMET) accepted a $44 bid from private equity interests, Icos (ICOS) agreed to a $34 deal with Eli Lilly (LLY), and Express Scripts (ESRX) made a surprise $58.50 cash and stock offer for Caremark (CMX), topping a bid by CVS.

Options’ trading volume leaders included Yahoo (YHOO), down 2.5%, Harrah’s (HET), up 3.5%, Altria (MO) up 0.5%, and General Electric (GE), up 1.7%. Joy Global (JOYG) gained 8% after reporting better than expected Q4 earnings; Navistar (NAV) fell 4% on news that the company would be dropped from the S&P 500 Index, replaced by Terex (TEX), up 9%.

Active implied volatility gainers were led by BHP Billiton (BHP), up 20% as energy prices faded; also higher was volatility for CVS, up 20% in deal-related trading, Sunoco (SUN), up 12%, ConocoPhillips (COP), up 11% and Hess (HES), up 9%. Volatility decliners were led by “deal” issues: BMET, down 67%, ICOS, down 55%, Harrah’s (HET), down 43%, and Penn Gaming (PENN), down 18%.

Note: Any stock or option symbols displayed are for informational purposes only and are not intended to portray a recommendation.