Top Percentage Gainers and Losers as of 10am 4/15/11 (AGO, OPXA, MBI, AMLN, ABMD, CTCT, CRUS, GGC, OTIV, SFG, BAC, LLY, ALKS)

Best

1) Opexa Therapeutics (NASDAQ: OPXA): Trading up 24% from yesterday's close to $2.27. A positive report emanating from a clinical trial of its drug Tovaxin has shares up.

2) Assured Guaranty (NYSE: AGO): Trading up 18.84% from yesterday's close to $16.84. Bank of America (NYSE: BAC) has agreed to pay Assured $1.1 billion to buy back defective mortgages.

3) MBIA (NYSE: MBI): Trading up 12% from yesterday's close to $10.00. Soleil Securities reiterated its Buy rating on shares of the company.

4) Amylin Pharmaceuticals (NASDAQ: AMLN): Trading up 10.12% from yesterday's close to $12.40. A positive recommendation from European Union regulators regarding a diabetes drug developed by Amylin, Eli Lilly & Co (NYSE: LLY), and Alkermes (NASDAQ: ALKS) has the stock up.

5) ABIOMED (NASDAQ: ABMD): Trading up 8.15% from yesterday's close to $16.32.

Worst

1) Constant Contact (NASDAQ: CTCT): Trading down 9.45% from yesterday's close to $31.08. The company was downgraded from Buy to Hold at Needham.

2) Cirrus Logic (NASDAQ: CRUS): Trading down 8.3% from yesterday's close to $16.59. Shares are sliding after the company lowered its margin outlook and reported manufacturing problems with one of its projects.

3) Georgia Gulf (NYSE: GGC): Trading down 7.8% from yesterday's close to $34.70.

4) On Track Innovations (NASDAQ: OTIV): Trading down 6.7% from yesterday's close to $2.51.

5) StancCorp Financial (NYSE: SFG): Trading down 5.8% from yesterday's close to $42.74.