NEW YORK (MarketWatch) -- Billionaire hedge-fund titan George Soros added to his stake in Argentine oil exploration company YPF YPF, +3.81% in the second quarter, buying more than 8.47 million depositary shares to make it the biggest single equity holding in his portfolio, worth $450.5 million as of June 30, according to a regulatory filing Thursday. Soros Fund Management added to stakes in insurer American International Group AIG, -0.13% and social-media site Facebook Inc. FB, -0.90% in the second quarter, while also loading up on puts on the SPDR S&P 500 ETF. The fund said it added nearly 1.758 million shares of AIG to its portfolio bringing its total stake to nearly 1.803 million shares as of June 30. Soros added 1.79 million shares of Facebook, bringing his stake to more than 1.841 million shares. Soros added 1.213 million shares of Apple Inc. AAPL, +0.49% bringing his total stake to nearly 1.834 million shares. In an apparent hedge, Soros also added nearly 9.7 million puts, which give him the option but not the obligation to sell the underlying S&P 500 ETF SPY, -0.02% bringing his total puts to nearly 11.3 million. He also added 1.745 million calls, which provide the option but not the obligation to buy the underlying ETF. Soros trimmed his position in Teva Pharmaceuticals TEVA, -1.20% by more than 3 million shares, leaving him with more than 7.272 million shares.
