A majority of Greek debtholders agree to the bond exchange deal to lift the markets higher during the midday with the Dow gaining 77 points to 12,915. Nasdaq climbed 31 points to 2967.

On the upside

Sequenom (Nasdaq: SQNM) reported a loss for the fourth quarter but revenue rose.

Threshold Pharmaceuticals (Nasdaq: THLD) narrowed fourth quarter losses more than expected.

Johnson & Johnson's (NYSE: JNJ) upbeat clinical trial results for its prostate cancer treatment Zytiga lifted shares of Medivation (Nasdaq: MDVN), which is developing its own prostate cancer medication.

On the downside

Williams-Sonoma (NYSE: WSM) announced the retirement of chief financial officer Sharon McCollam.

Dynegy (NYSE: DYN) widened fourth quarter losses more than expected as revenue tumbled.

Shares of ZELTIQ Aesthetics (Nasdaq: ZLTQ) fell for the third day after the medical technology company reported a wider than expected fourth quarter loss.

In the broad market, advancing issues outpaced decliners by a margin of nearly 7 to 2 on the NYSE and by 2 to 1 on Nasdaq. The Russell 2000 which tracks small cap stocks climbed 7 points to 803.