As of March 31, Wells Fargo was Buffett's second largest stock investment at $13.2 billion or 7.42% of the company's shares, while he held 13% of American Express shares worth over $8.8 billion, and $2.2 billion worth of U.S. Bancorp shares, or 3.6% of the company's float. But even without Buffett's buyback math, the expected earnings prospects of traditional mortgage and credit card lenders may trump capital markets oriented players. In March, we noted that because of Wells Fargo's near 30% annual earnings growth trajectory, Buffett may end 2012 as the largest investor in America's most profitable bank. After JPMorgan unveiled a derivatives related trading loss in May that may exceed $2 billion, Wall Street analysts now project that Wells Fargo will end 2012 as the most profitable U.S. bank, earning $17.7 billion for the year, according to Bloomberg compilations of forecasts. That contrasts to the $17.2 billion in adjusted net income that JPMorgan is expected to earn this year. Wells Fargo will earn the lion's share of its profit and revenue from mortgage, business and credit card lending, while JPMorgan's earnings will be a mix of those businesses and its global investment banking operations. It's the distinction between Wells Fargo's quick earnings ascendance relative to JPMorgan - the longtime profit leader throughout the financial sector - that may best exemplify the simplicity of Buffett's investing plan relative to the elusive allure of investment banking profits. JPMorgan, like Goldman Sachs is undoubtedly a leader in investment banking, with a top three position in most key merger advisory and debt and equity underwriting markets. Still, a near 30% year-over-year lull in those businesses means that even top brands aren't expected to post strong earnings. In fact, it's the counterintuitive accounting gains that investment banks may post on the falling value of their debt after Moody's slashed sector ratings that may be among the biggest positive surprises in second quarter earnings. Although many like JPMorgan chief executive Jamie Dimon expect that investment banking revenues will have a big comeback as companies enter a cycle of mergers and IPOs that was postponed by the European debt crisis and political gridlock in Washington, some think the industry's woes may be lasting.