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After-hours buzz: AAL, DAL, UAL & more

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Check out which companies are making headlines after the bell on Monday:

Airline stocks were soaring in extended trade Monday. Shares of American Airlines, Delta Air Lines and United were all up more than 2 percent after the bell.

The increase comes after SEC filings showed that Warren Buffett's Berkshire Hathaway took stakes in three of the four major airlines. The move into airlines is a shocking reversal for Buffett, who has shunned the industry for decades following a volatile investment he made in US Airways back in 1989. He bought $358 million in preferred shares of US Airways, which almost immediately dropped in value.

Shares of Southwest Airlines were also up more than 3 percent after the bell. CNBC confirmed that Berkshire Hathaway has also taken a stake in the airline.

SEC filings detailing Berkshire's stake in American, Delta and United only reflect purchases made through September 30. He told CNBC about his stake in Southwest because of his friendship with the airline's co-founder Herb Kelleher and because he did not want investors to think he was avoiding the company.

Advance Auto Parts saw its stock jump more than 11 percent in extended trading. The automotive aftermarket parts provider announced third-quarter results that beat on both the top and bottom lines. The company reported adjusted earnings per share of $1.73, beating expectations of $1.70 EPS. It posted revenue of $2.25 billion, beating estimates of $2.2 billion.

Hospital Corporation of America was up more than 1 percent after the bell. The company's board of directors announced a $2 billion share repurchase program Monday after the market closed. It previously announced a $3 billion share repurchase in October 2015.

—CNBC's Becky Quick contributed to this report.