Idenix Pharmaceuticals Inc (NASDAQ:IDIX), Family Dollar Stores, Inc. (NYSE:FDO) and Receptos Inc (NASDAQ:RCPT) started off the week strong and are Wall Street’s top gainers midday. On the losing end are Pilgrim’s Pride Corporation (NASDAQ:PPC), Melco Crown Entertainment Ltd (ADR) (NASDAQ:MPEL) and Dot Hill Systems Corp. (NASDAQ:HILL).

chart_1 (35) Idenix

Idenix Soars on News of Merck Purchase

The share price of Idenix Pharmaceuticals Inc (NASDAQ:IDIX) surged an impressive +232.92%, rendering it today’s top midday gainer. Merck & Co. revealed plans today to purchase Idenix in a deal valued at $3.85 billion. Baupost Group head Seth Klarman holds 53.3 million IDIX shares and stands to make a major profit on the purchase.

Family Dollar Stores, Inc. (NYSE:FDO) jumped +13.51% today – largely the result of billionaire Carl Icahn’s disclosure of a 9.4% stake in the company at market close on Friday. John Paulson is also a Family Dollar shareholder and initiated his position in early 2013.

Rounding out this Monday’s list of midday gainers is Receptos Inc (NASDAQ:RCPT), the price of which rallied +10.81%. Thomas Steyer upped his ante in the biopharmaceutical company significantly in Q1, picking up 300,000 shares. The firm has had a rough to in recent months and is down -37.56% over the past 90 days.

Pilgrim’s Pride Drops Hillshire Bid

Pilgrim’s Pride Corporation (NASDAQ:PPC) dipped -5.56% today in the wake of the company’s announcement that it has withdrawn its proposal to acquire Hillshire Brands, opening the door for Tyson Foods to succeed in its own bid. Hedge fund manager George Soros purchased 56,000 PPC assets during the first quarter of this year.

Down -4.95% midday, Melco Crown Entertainment Ltd (ADR) (NASDAQ:MPEL) continues to feel the effects of cautious notes issued by analysts on Friday. The casino gaming and entertainment resort operator is also a Soros pick.

Yet another Soros bet, Dot Hill Systems Corp. (NASDAQ:HILL), had a rough start to the day as well, its price falling -4.08% by midday. The company said today that it had signed a reseller agreement with VMsources Group and in general has had a positive year, its price up +27.89% since the start of 2014.