Top Percentage Gainers And Losers As Of 12 p.m. 4/12/2011 (SKH, JPM, CYH, THC, SIFY, TIBX, HPQ, IDIX, BAC, CCRT, WMS, EXTR, SB, PSTR, GLUU, UAL, GIL, DRRX, SGI, AIB)

Best

1) Skilled Healthcare Group (NYSE: SKH): Stock has ascended 10.56% to $15.50. The company recently retained J.P. Morgan (NYSE: JPM) to assist in a possible future sale of the company. Had been up as much as 14% earlier in the session.

2) Community Health Systems (NYSE: CYH): Shares are jumping 8.96% to $28.24 as skepticism grows about Tenet Healthcare’s (NYSE: THC) lawsuit against the company. The stock took a huge hit in yesterday’s session, trading down as low as $22.32 after Tenet’s lawsuit alleging illegal admission of patients in order to benefit financially came to light. The stock is gaining despite a downgrade from Above Average to Average at Caris.

3) Sify Technologies (NASDAQ: SIFY): Stock is up 7.74% to $4.87, sitting just below the 52-week high ($4.88) it had set earlier in the session.

4) TIBCO Software (NASDAQ: TIBX): Shares are trading 7.37% to the upside at $28.94. News surfaced that Hewlett-Packard (NYSE: HPQ) explored a possible purchase of the company two weeks ago. No reason has been given as to why the talks broke down.

5) Idenix Pharmaceuticals (NASDAQ: IDIX): Stock has gained 6.58% to $3.40 after starting the day in negative territory. The company was upgraded from Neutral to Buy at Bank of America (NYSE: BAC) yesterday.

Other notable movers: Glu Mobile (NASDAQ: GLUU): Up 6.16% to $3.87; United Continental Holdings (NYSE: UAL): Up 5.9% to 21.73; Gildan Activewear (NYSE: GIL): Up 5.79% to $33.88.

Worst

1) CompuCredit Holdings (NASDAQ: CCRT): Equity is continuing to slide, currently putting in a 17.22% loss to $5.48.

2) WMS Industries (NYSE: WMS): Shares are taking a 16.4% haircut to $20.86 after missing Wall Street earnings estimates yesterday.

3) Extreme Networks (NASDAQ: EXTR): Currently trading down 11.21% to $3.01 after missing sales estimates for the third-quarter. Bloomberg had estimated sales of $83.9 million. The company said the number would be $76.5 million at most.

4) Safe Bulkers (NYSE: SB): Shares are losing 10.48% to $8.29. The company is offering 5 million shares at a 9.3% discount to Monday’s closing price.

5) PostRock Energy Corporation (NASDAQ: PSTR): After starting the day neutral, the stock has fallen 10.23% to $6.93.

Other notable movers: Durect Corporation (NASDAQ: DRRX): Down 9.71% to $3.16; Allied Irish Banks (NYSE: AIB): Down 9.14% to $3.18; Silicon Graphics International (NASDAQ: SGI): Down 9.29% to $18.35.