Wells Fargo (WFC) is Berkshire's biggest holding by far. It makes up more than 20% of the company's investment portfolio.
The Oracle of Omaha absolutely loves the financial sector. Four of Berkshire's top 10 investments are financial firms.
Berkshire also owns sizable stakes in Goldman Sachs (GS), Bank of New York Mellon (BK) as well as $5 billion in preferred shares of Bank of America (BAC).
Related: Don't expect a rate hike just yet
But low interest rates are hurting the profit margins for big banks -- including mortgage powerhouse Wells Fargo.
Things could improve once the Fed finally raises rates. For now though, Wells Fargo is a market laggard even though its widely viewed as one of the best run big banks.
