A New York Stock Exchange Inc. hearing panel has fined Prudential Equity Group $850,000 for failing to supervise internal electronic mail adequately.

Prudential Equity, part of Prudential Financial Inc., Newark, was supposed to keep electronic logs showing supervisors had reviewed the messages, but the logs were purged, the panel charged. In all, the supervisory approval logs of about 140 of the firm’s 256 domestic retail branches along with its research department and other units were deleted from 1999 through August 2002.

The loss of the messages, including some e-mails from company clients, affected at least 2 investigations by the NYSE’s Division of Enforcement, the panel charged.

Prudential Equity agreed to the penalty but did not admit to any wrongdoing in the case.