Today’s midday gainers are Idenix Pharmaceuticals Inc (NASDAQ:IDIX), TAL Education Group (ADR) (NYSE:XRS), PDC Energy Inc (NASDAQ:PDCE). The midday losers: Apple Inc. (NASDAQ:AAPL), International Tower Hill Mines Ltd (NYSEMKT:THM) and Enzon Pharmaceuticals Inc (NASDAQ:ENZN).

Apple Inc.

Idenix Pharmaceuticals is today’s top gainer

Topping off our midday gainers list this Tuesday is Idenix Pharmaceuticals Inc (NASDAQ:IDIX), which shot up +14.35% to reach $7.86. Billionaire Seth Klarman holds 39.8 million shares of the pharmaceuticals company – nearly 4.5% of his portfolio. According to his 13F filings, Klarman has been increasing his position in IDIX since June 2011.

Following Idenix Pharmaceuticals Inc (IDIX) is TAL Education Group (ADR) (NYSE:XRS), its stock price increasing +13.65% today. Two of the billionaires tracked by iBillionaire hold positions in this company: Tiger Global, which owns 3.5 million shares (1.08% of the fund), and Richard Chilton, with 40,000 assets (less than 1% of his portfolio).

Rounding out today’s list is PDC Energy Inc (NASDAQ:PDCE), which surged +12.10% to $50.72. Brazilian billionaire Jorge Lemann is the owner of 100,000 shares of the energy company (a 0.63% exposure). And George Soros holds an additional 100,000 assets, acquired at an average $55.90 each.

Apple loses with its sales report

Tech giant Apple Inc. (NASDAQ:AAPL) took a dive today following the release of a disappointing sales report yesterday afternoon. It dropped -7.88% to $507.12. AAPL is a favorite among a number of our billionaires, especially David Einhorn, who owns 2.39 million shares (20.29% of his portfolio). Activist investor Carl Icahn holds 2.39 million shares of the company as well. Other investors with a position in AAPL are David Tepper (a 1.85% exposure), George Soros (0.34%), Ray Dalio (0.10%) and Richard Chilton (0.01%).

Second is International Tower Hill Mines Ltd (NYSEMKT:THM), its share price decreasing -5.06% to hit $0.60. The only billionaire tracked by iBillionaire with a position in the mineral company is John Paulson, who acquired his nearly nine million shares at an average price of $4.77 each.

Last up is Enzon Pharmaceuticals Inc (NASDAQ:ENZN), which dropped -2.76% today. Seth Klarman owns 4.3 million ENZN shares – 0.26% of his fund. Carl Icahn has nearly six million shares.