Shares of American International Group (NYSE:AIG) fell roughly 31% today as investors continue to worry about other financial institutions that might file for bankruptcy protection due to a lack of credit available in the market. Companies investors are worried most about include Lehman Brothers (NYSE:LEH), down 13.5%, which is shopping for a buyer this weekend, Washington Mutual (NYSE:WM), down 3.5%,  which has similar credit issues due to mortgages that it currently holds as Lehman and AIG, and Merrill Lynch (NYSE:MER), down 12.25%, for the same stated earlier reasons. By Steve Patterson AIG Looking Hard for Capital AIG has ...