The investigation into trading abuses in the mutual fund industry could result in possible regulatory action against the president of

National Securities

, as well as a fine against the brokerage, according to several recent filings.

Separately,

Oppenheimer & Co.

(OPY) - Get Report

disclosed Thursday for the first time that some of its brokers "may have engaged in the activities that are the subject" of inquiry into mutual fund trading abuses. Oppenheimer is home to Michael Sassano, once

one of Wall Street's most successful mutual fund timing brokers.

The NASD recently notified Michael Bresner, National's president, that he could face regulatory action, according to his brokerage registration statement. The NASD is investigating allegations of market-timing and late trading at National, a subsidiary of

Olympic Cascade Financial

( OLY).

Regulators are focusing on potentially improper trading at National from October 2000 to February 2003.

"As president of the firm at the time of the alleged misconduct, I am being investigated for my supervisory role with respect to that conduct,'' said Bresner, in disclosing that he had a so-called Wells notice from regulators in April.

Market-timing is the frequent trading of mutual fund shares, a practice that most mutual fund families say they prohibit. Late trading is the illegal practice in which someone buys shares of a mutual fund after their 4 p.m. closing price in order to take advantage of late-breaking, market-moving news.

In an interview with

TheStreet.com

on Thursday, Bresner wouldn't discuss the details of the investigation. But he said, "we're in the process of trying to settle it.''

In a recent corporate filing, the firm said it is trying to negotiate a settlement with the NASD. The firm said a possible resolution could result in the payment of a $600,000. The corporate filing made no mention of the potential regulatory action against Bresner.

While New York Attorney General Eliot Spitzer and the

Securities and Exchange Commission

snared much of the attention in the nearly yearlong mutual fund investigation, the NASD lately has become more active in pursuing its own cases of market-timing and late trading.

As for Oppenheimer, the brokerage said it has been providing documents to the SEC as part of an "of an industrywide review of market-timing, late trading and other activities involving mutual funds." Oppenheimer, in a corporate filing, said the inquiries have focused both on the firm's brokerage division and its clearing operation.

Oppenheimer said the SEC inquiry is not a "formal investigation.'' The firm also said there "is no evidence that either the company or its employees were engaged in 'late trading.''' It said only a "very limited number'' of brokers may have engaged in improper contact.

The filing makes no mention of Sassano and the firm's decision earlier this year to disband his 15-member cadre of junior brokers, clerks and traders. At its peak, the Sassano team

generated $15 million in annual commissions, much of it from placing market-timing trades for an A-list of hedge fund customers.

Sassano has been suspended from doing any further work for the firm. In February, Sassano changed his official place of work from Oppenheimer's office in lower Manhattan to his parents' home in Mirimar Beach, Fla.