Berkshire Hathaway Inc. (BRK.A) (BRK.B) bought more shares of Apple Inc. (AAPL) in the second quarter, according to an SEC filing Tuesday.

Warren Buffett's investment vehicle added more than 12 million shares of the iPhone maker during the quarter bringing its holdings to nearly 252 million shares worth more than $50 billion, a 13F filing showed.

Apple became the first company to top $1 trillion in market value earlier this month, after investors reacted positively to its latest financial results.

Buffett was also active in airlines and financial stocks.

Berkshire trimmed its holdings in United Continental Holdings Inc. (UAL) and American Airlines Group Inc. (AAL) but added 10 million shares of Delta Air Lines Inc. (DAL) and more than 8 million shares of Southwest Airlines Co. (LUV) .

It also added 2.2 million shares of Goldman Sachs Group Inc. (GS) to its holdings, and an additional 9 million shares of U.S. Bancorp. (USB) , according to the filing.

Berkshire also picked up almost 1.4 million shares of General Motors Co. (GM) .

The company exited its position in Verisk Analytics Inc. (VRSK) .

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