Standard & Poor's informed several European governments of possible credit downgrades sending the markets tumbling to a lower open with the Dow plunging 133 points to 12,337. Nasdaq dropped 28 points to 2696.

On the upside

Westlake Chemical offered approximately $1.03 billion in cash to acquire Georgia Gulf (NYSE: GGC).

Radian Group (NYSE: RDN) wrote $6.5 billion in new mortgage insurance during the fourth quarter.

SAP AG (NYSE: SAP) reported record revenue for the fourth quarter as well as the full year.

On the downside

Archer Daniels Midland (NYSE: ADM) will end its Telles biodegradable plastics joint venture with Metabolix (Nasdaq: MBLX).

Raymond James downgraded JA Solar Holdings (Nasdaq: JASO) to an Underperform rating.

The Wall Street Journal reported that federal prosecutors initiated an investigation into possible accounting violations by Diamond Foods (Nasdaq: DMND).

In the broad market, declining issues outpaced advancers by a margin of more than 4 to 1 on both the NYSE and on Nasdaq. The Russell 2000 which tracks small cap stocks tumbled 9 points to 761.