Credit agency Moody’s has downgraded the credit ratings of 15 of the world’s biggest banks, saying all are at risk of major losses. The downgraded banks include Morgan Stanley, Citigroup, Goldman Sachs, Bank of America, Deutsche Bank, Credit Suisse and JPMorgan Chase, which recently lost $3 billion on risky bets. In a statement, a Moody’s executive said the banks “have significant exposure to the volatility and risk of outsized losses inherent to capital market activities.”