Warren Buffett's Berkshire Hathaway ditched the 'big four' airline stocks in April, driving $6.1 billion in stock sales

· *Warren Buffett's Berkshire Hathaway sold the "big four" airline stocks in April, the famed investor revealed at Berkshire Hathaway's annual meeting on Saturday.*
· *"It turned out I was wrong," Buffett said about his decision to invest in American, Delta, United, and Southwest.*
· *Berkshire's first-quarter earnings...