The new rule stems from SEC Chairman Arthur Levitt's crusade against so-called selective disclosure that benefits market professionals at the expense of small investors.

Possessing market-moving information - about such things as earnings forecasts, mergers and new products - has at times allowed Wall Street brokerage firms and their best customers to reap trading profits before most investors get the news.

"Simply put, these practices defy the principles of integrity and fairness," Mr. Levitt said Thursday. The new rule applies only to senior executives, not lower-level executives in their communications with customers and suppliers. The SEC also said the rule doesn't apply to analysts' routine conversations with midlevel company executives.

Other kinds of communications, including company contact with journalists and securities-ratings firms, such as Moody's Investors Service Inc., also are exempt.

Dow Jones & Co., publisher of The Wall Street Journal and WSJ.com, had objected that the original proposal could inhibit reporters' interviews with corporate executives, interfering with constitutional rights under the First Amendment.

"We said we were concerned that the original language could be interpreted to inhibit the free flow of information to journalists," said Richard Tofel, a Dow Jones spokesman. "We're pleased with the result." Passage by the four-person commission by a 3-1 vote, with Commissioner Laura Unger dissenting, was unusual for its contentiousness. Nearly all regulations have been approved unanimously during Mr. Levitt's tenure of more than seven years. Mr. Levitt said several revisions were made to satisfy concerns of Commissioner Isaac Hunt, who agreed to support the measure only in the past several days.

For instance, the final draft makes it clear that violating the disclosure rules isn't considered fraud. Violations are punishable with injunctions and fines.The regulation also insulates companies from private lawsuits arising from violations of the new rule. By making failure to comply with the rule a disclosure violation, the SEC gets around its historical problem in fighting selectie disclosure. In a handful of unsuccessful enforcement cases, the SEC tried to prove selective disclosure was a fraud violation. One celebrated decade-long case went to the Supreme Court, which ruled against the SEC in 1983.

SEC officials said the disclosure requirement was never intended to apply to communication between executives and journalists, and that the final rule clarifies the issue. Furthermore, applying the rule to journalists could have raised First Amendment issues, they said.

At Mr. Hunt's request, the SEC also agreed to do a study down the road assessing whether the new rule has any adverse effects. The rule "is an important first step in making the markets even fairer," he said.The measure requires public corporations whose senior executives intentionally disclose market-moving information to a few market professionals to make the information public simultaneously, either by issuing a news release or filing the information with the SEC. Posting the information on the Internet isn't sufficient disclosure because not all investors have computers, the SEC said.

The rule creates one possible loophole. Submitting the information to the SEC could undermine the rule's intent because SEC filings take at least 24 hours to be posted on the regulator's Web site.Inadvertent selective disclosure, such as an off-the-cuff remark in a chance meeting or phone call, would have to be publicized as soon as possible after the fact, generally within 24 hours.

In her dissenting comments, Ms. Unger said the rule is "overreaching." "Will the regulation provide information investors want? I'm not convinced it will," she said. James Brinkley, president of the Legg Mason Wood Walker securities unit of Legg Mason Inc. and chairman of the Securities Industry Association trade group on Wall Street, said the group was concerned that the new rule would result in "less information rather than more."