Today’s top gainers midday are Questcor Pharmaceuticals Inc (NASDAQ:QCOR), Idenix Pharmaceuticals Inc (NASDAQ:IDIX) and Sarepta Therapeutics Inc (NASDAQ:SRPT). The losers are Sears Holdings Corp (NASDAQ:SHLD), Criteo SA (ADR) (NASDAQ:CRTO) and Intrexon Corp (NYSE:XON).

chart_1 (3) Sears

Questcor Soars on Mallinckrodt Buy

This Monday’s top midday gainer honor goes to Questcor Pharmaceuticals Inc (NASDAQ:QCOR), the price of which surged +17.73%. The company is being purchased by Mallinckrodt (NYSE:MNK) for $5.2 billion in cash and stock. Questcor and Mallinckrodt are part of John Paulson’s portfolio.

Second comes Idenix Pharmaceuticals Inc (NASDAQ:IDIX), up +11.22%. The Seth Klarman pick recovered from last week’s slide, which saw the shares tumble -11.17% in five days. The recovery is fueled by the company’s announcement of promising clinical data from its newest developments.

Another biotech company, Sarepta Therapeutics Inc (NASDAQ:SRPT), takes today’s third spot, up +2.52% midday. The share price of the George Soros allocation has increased +14.48% YTD.

Sears, Lands’ End Take a Dive

On the losing end is Sears Holdings Corp (NASDAQ:SHLD), its price down -19.10% following today’s Lands’ End IPO. Shares of the now publicly-traded spin-off also tumbled -8.59%. Bruce Berkowitz is a SHLD shareholder, as is Edward Lampert, the retailer’s CEO.

It’s also been a rough Monday for Criteo SA (ADR) (NASDAQ:CRTO), the price of which decreased -8.94%. Its shares are down -31.63% since the announcement of a public offering mid-March. CRTO is part of Tiger Global’s investment fund.

Intrexon Corp (NYSE:XON), a company in the emerging synthetic biology field, slipped -7.56% after posting financial results last week. Since posting financial results on April 3rd, its share price has been cut by -15.48%. Daniel Loeb, David Einhorn and Boone Pickens have placed bets on this one.