The Securities and Exchange Commission (SEC) is considering new rules that would prevent financial firms from masking the risks they take by temporarily lowering their debt levels before quarterly reports to the public are due. SEC Chairwoman Mary Schapiro’s disclosure, at a hearing of the House Committee on Financial Services, came two weeks after it was reported that 18 large banks had consistently lowered one type of debt at the end of each of the past five quarters, reducing it on average by 42% from quarterly peaks.