SAN FRANCISCO (CNN/Money) - Way back in a quaint era of stock market scrutiny -- about two years ago -- the Securities and Exchange Commission enacted Regulation FD, which stood for fair disclosure and mandated that public companies give stock-moving information to all investors at once.

How simple that debate seems now, what with our focus on abuses of the public trust far worse than the old wink-wink/nudge-nudge game of earnings guidance CFOs used to play with analysts.

And yet, FD was a huge debate. The SEC even invited a few interested parties -- including me -- to a day-long discussion of the regulation's merits in April, 2001. At the time, all we had to measure FD were the gripes of a bunch of investor-relations folks and securities analysts, who said the regulation was keeping information from getting into the marketplace.

Now, thanks to two academics associated with the Stern School of Business at New York University, we have far more than whining. On the contrary, we have statistical evidence that FD is doing the job the SEC set out for it to do. In an article in the school's magazine, STERNbusiness, finance professors Partha Mohanram (of NYU) and Shyam Sunder (a Stern PhD now teaching at Northwestern's Kellogg school) show with statistical clarity that Regulation FD has succeeded in leveling the playing field.

Reg FD has a basic goal: Stop companies from selectively disclosing certain information to favored analysts. The rule made it clear that material information, the kind that moves stocks, needed to be disseminated widely. In other words, disclosure over dinner was out; conference call Webcasts were in.

Mohanram and Sunder measured analyst forecasting error for two eight-month periods, first in 1999-2000 and again in 2000-2001. They used various statistical methods to strip out the varying stock-market performances during those periods, and they came up with some surprising conclusions. First, while analysts' ability to forecast earnings hasn't changed much on average, there's now a wider range of forecasts. Translation: Analysts are forced to go it alone more.

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Second, analysts are finding additional sources of information to compensate for some loss in information coming directly from companies. Third, analysts who were stars before FD aren't maintaining their edge. The implication is that relationships matter less than hard work. That was precisely one of the goals of FD.

In times when CFOs are being fired for fabricating their MBAs and are being perp-walked for allegedly bilking their companies, paying attention to pedantic issues like selective disclosure may seem trivial. But it isn't. Reg FD shows that regulators were trying to make the market fairer, even before the situation got really bad. And it shows that even when the securities industry screams, it's worth staying the course on valuable public policy.

Strolling through the lobby of a very large New York Stock Exchange-listed company the other day, I noted a cover story in NYSE Magazine, which bills itself as being "At the Center of Global Business." The cover, from a late-2001 edition, featured a smiling, gray-haired executive with the headline, "The Brown Agenda; CEO Dick Brown declares 'EDS is back.'" Oh well, no one's perfect.

Adam Lashinsky is a senior writer for Fortune magazine. Send e-mail to Adam at lashinskysbottomline@yahoo.com.

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