'Big 4' airline stocks plummet after Warren Buffett revealed that Berkshire Hathaway dumped them in April

· *The "big four" US airline stocks plummeted as much as 10% in pre-market trading on Monday.*
· *Warren Buffett sold his roughly 10% stakes in American, Delta, United, and Southwest in April, he revealed during Berkshire Hathaway's annual meeting on Saturday.*
· *"Our airline position was a mistake," the famed investor...