Piper Jaffray and Co. was fined $700,000 by the Financial Industry Regulatory Authority Inc. for failing to retain e-mails.
Finra on Monday said the firm failed to keep 4.3 million e-mails from late 2002 through 2008, due to intermittent technical issues with retention and retrieval.
The problem came to light after Finra asked Piper for an electronic version of a hard-copy e-mail the regulator had obtained during a separate investigation.
Only then did the firm inform Finra of the retention issues, Finra said.
The firm settled the charges without admitting or denying the charges. A spokeswoman for Piper Jaffray was not available for comment.
The retention failures occurred despite the fact that Piper was required to review and certify its e-mail retention systems as part of the 2003 global research settlement, Finra said.