Major U.S. banks masked risk levels: report 8:36am EDT (Reuters) - Major U.S. banks temporarily lowered their debt levels just before reporting in the past five quarters, making it appear their balance sheets were less risky, the Wall Street Journal said, citing data from the Federal Reserve Bank of New York. The paper said on Friday 18 banks, including Goldman Sachs Group , Morgan Stanley , J.P. Morgan Chase Bank of America and Citigroup , understated the debt levels used to fund securities trades by lowering them an average of 42 percent at the end of each period. The banks...