An employee at the Securities and Exchange Commission has accused the regulatory agency of destroying at least 9,000 documents relating to inquiries of Wall Street banks and hedge funds. Documents that were destroyed related to corporate giants including Goldman Sachs Group, Deutsche Bank, Lehman Brothers, Citigroup, Morgan Stanley, Wells Fargo, Bank of America, convicted fraud operator Bernard Madoff and hedge fund SAC Capital Advisors, according to a letter from the employee’s attorney released Wednesday by Sen. Charles E. Grassley (R-Iowa). Darcy Flynn, an attorney at the SEC, says the agency followed a policy of systematically destroying documents after closing what are known as “matters under inquiry,” or MUIs, which are the agency’s preliminary look into a potential violation of securities laws. In closing the matters under inquiry, the SEC decided not to proceed to a formal investigation.