The investment bank U.S. Bancorp Piper Jaffray had to pay the piper Tuesday to settle charges that one of its top officials threatened to withhold research coverage of a drug company unless the company rewarded it with a lucrative stock underwriting deal.

As is customary in such settlements, Piper Jaffray, a division of Minneapolis-based

U.S. Bancorp

(USB) - Get Report

,didn't admit to any wrongdoing in agreeing to pay a $300,000 fine to the

National Association of Securities Dealers

. But the agreement with the NASD is a strong sign that securities regulators are getting serious about forcing Wall Street to clean up its act, especially amid all the investor doubts about the ability of brokerages to deliver honest stock analysis.

"Brokerage firms and their executives cannot use threats regarding research activities as a way to obtain investment banking business," said Mary Schapiro, president of the NASD's regulatory arm, in a prepared statement.

The NASD charges that last December, Piper Jaffray Managing Director Scott Beardsley threatened to drop analyst coverage of

Antigenics

(AGEN) - Get Report

if the pharmaceutical company didn't select the investment bank as the lead underwriter on a planned secondary stock offering. After Antigenics selected another investment bank to serve as the lead underwriter, Piper Jaffray allegedly retaliated by following through on its threat and discontinuing its research coverage on Jan. 2.

Piper Jaffray was the lead underwriter on a February 2000 initial public offering for Antigenics, which develops cancer-treatment and autoimmune-fighting drugs. Last December, just before the investment bank dropped coverage, its analysts following Antigenics had a strong buy rating on the stock.

Of the $300,000 fine levied by the NASD, $50,000 was assessed directly against Beardsley, who also did not admit to the charges. The NASD also imposed a censure on both the firm and Beardsley. In a prepared statement, Piper Jaffray says the settlement is in the "best interests of our clients and business."