US regulators have defended their decision to impose fines of only $8.3m (€8.3m) on five Wall Street firms for failing to retain proper email records.

Deutsche Bank, Goldman Sachs, Morgan Stanley, Salomon Smith Barney (SSB) and US Bancorp Piper Jaffray each received $1.65m in fines for violating rules on record-keeping. The Securities and Exchange Commission (SEC), NASD and the New York Stock Exchange jointly imposed the fines.