Moody’s Investors Service downgraded the debt ratings of 15 major international banks and securities firms on Thursday, a move that could cost the banks billions of dollars in extra collateral…U.S banks that were downgraded included: Bank of America, Citigroup, Goldman Sachs, JPMorgan, and Morgan Stanley. “All of the banks affected by today’s actions have significant exposure to the volatility and risk of outsized losses inherent to capital markets activities,” Moody’s said in a statement. “However, they also engage in other, often market leading business activities that are central to Moody’s assessment of their credit profiles,” the firm added. “These activities can provide important ‘shock absorbers’ that mitigate the potential volatility of capital markets operations, but they also present unique risks and challenges.” [CNBC, related]