That other bank, of course, is Bank of New York Mellon ( BK), a $26 billion financial services stock that doesn't have the same household name status that Wells Fargo does. And that's for good reason. BNY Mellon built its business around serving other financial firms' back office needs, building itself as one of the biggest asset custodians in the industry, and establishing a big presence as an asset manager. That means that BNY Mellon isn't interested in writing you a mortgage, but it is very interested in keeping an eye on your other accounts in exchange for fees. Those fee-based businesses are attractive because they don't come with the potential balance sheet black holes that traditional risk-taking banks do. With a quiet stock rally going in full force as we enter the Fall, BNY should see its custody accounts start to swell when investors start to realize what's going on. And with hefty net profit margins from fees, it should be able to pass even more cash onto investors through a 2.3% dividend yield that's going to be subject to less regulatory scrutiny than WFC's. Berkshire agrees. The firm bought 13.11 million shares of BNY Mellon in the past quarter, tripling its position in the firm and piling its position to nearly half-a-billion dollars. If you have to pick between one of BRK's banks, I'd suggest going with BK. To see the rest of Warren Buffett's plays - including a complete list of which stocks he added or sold off, check out the Warren Buffett Portfolio on Stockpickr. -- Written by Jonas Elmerraji in Baltimore.