It's a given that Warren Buffett's Berkshire Hathaway is a titan in the investment world, with interests ranging from insurance giant Geico to confectionery maker See's Candies. The conglomerate also holds large equity stakes in blue-chip companies.

Berkshire Hathaway is arguably always Buffett's favorite stock. But another stock commands a strong second place.

Though Warren Buffett's firm missed out on some gains, Berkshire's Apple trade will likely go down as one of its best in history.