So it should come as no surprise that Wells was Berkshire's second-biggest add-on position in the second quarter. The Omaha-based firm picked up 16.7 million shares, bringing the firm's total stake to a whopping $13.75 billion.>>10 Bank Stock Value Picks Here's the thing: It's hard to argue with Buffett's opinion on Wells. Yes, the company is the best of the big-four banks, in part because it's a decent stock and in part because the other three are writhing creatures that frighten most investors by mere mention of their ticker symbols (I won't dare mention them here). The long and short of the Wells Fargo investment thesis is simple: Wells avoided the mistakes that its peers made before the credit crisis, and now it's in prime position to grow earnings even faster while its share price plays catch-up. If you're looking to buy a big bank, by all means, follow Warren's example and buy Wells Fargo. But if you don't want a big bank in your portfolio, I don't blame you. In fact, I think Berkshire's other bank purchase is more appealing. Wells Fargo, also one of Bruce Berkowitz's holdings, shows up on a recent list of 8 Undervalued Stocks Getting Help From the U.S.