Day trading can't be stopped, and there are sound economic reasons why it should not be. But just as bartenders who ply drunken customers with drinks should be held responsible for the consequences, day trading firms should be held to the same standard. PNS commentator Gregory J. Millman is the author of "The Day Traders," forthcoming from Times Books. Millman's previous book, "The Vandals' Crown -- How Rebel Currency Traders Overthrew the World's Central Banks" (Free Press, 1995), was translated into nine languages and became a Business Week best seller.

NEW YORK -- We'll never fully understand why Mark O. Barton went on his murderous rampage in Atlanta. But the bitter truth is that the day trading firms he targeted probably deserve to share the blame.

During the year I spent researching a book on the day trading industry, I became quite familiar with All-Tech Investment Group and Momentum Securities, the two firms in whose offices Barton launched his shooting spree. By the standards of the industry, they are relatively responsible outfits. A newly proposed National Association of Security Dealers (NASD) rule announced July 29 would require day-trading firms to disclose risk and screen customers for suitability before allowing them to open an account. All-Tech and Momentum already do at least some of this.

On the other hand, no instructor I heard during All-Tech's month-long training program suggested that day trading would be a quick and easy road to riches. They repeatedly warned novices that day trading is difficult to master and not for everyone. They told trainees that day trading demands intense focus and discipline, a keen mind, fast reflexes and capital.

Momentum president James Lee, who is also president of the day-trading industry group the Electronic Trading Association, has said the same things to the press and on the group's web site.

But day trading firms rarely seem to turn away anyone who lacks these requirements. In practice, almost anyone with capital to open an account is welcome to day trade -- and pay commissions. If aspiring day traders don't have enough capital, brokers often suggest that they borrow it. No one makes having a keen mind, or fast reflexes a sticking point for joining the fray. In one firm I met a 73-year old retired public-school secretary seated at a powerful trading floor workstation betting her nest egg against the best professionals in the market. No one stopped her. I've met self-confessed gambling addicts, people who admitted that they put their life savings into their day trading account, lost it, and borrowed wherever they could to re-capitalize the account. No one stopped them. They traded as long as the money held out. But when the money went, hope went too, and sometimes the consequences were fatal.

Mark O. Barton's last note said he planned to kill "the people that greedily sought my destruction." Was he a madman? Doubtless. But in a year of reporting, I had already heard of two suicides by day traders -- one, a failed attempt that left a man an invalid -- before Mark O. Barton's massacre and suicide. A psychotherapist who treats many day traders told me that this style of trading is often pathologically addictive.

Day trading firms encourage their customers to trade frequently, without thinking much, and to accept losses as part of the learning curve. "Trade frequently" is an understatement. Court papers filed by Momentum in a lawsuit said that many of the firm's customers traded from one to three hundred times per day, and since the firm charged fifteen dollars commission for each trade, a single customer could generate forty-five hundred dollars in commission revenues each day. This is not out of line with other day-trading firms.

Trading this actively does not allow much time for analysis and reflection. But day trading is not about analysis and reflection. Training programs teach aspiring day traders that thinking interferes with success, because when the market is moving, thinking means missing opportunities. Instead, aspiring traders are told that they must learn to react instinctively.

Of course, people who trade a hundred times a day without thinking may be expected to lose money. Neophyte day traders are told to expect three to six months of losses before they begin to win. But by then, they are often hooked -- and eventually, most of them are busted.

Day trading can't be stopped, and there are sound economic reasons why it should not be. But a bartender who keeps serving someone obviously drunk may be held responsible for the consequences. Day trading firms should be held to the same standard. The newly proposed NASD rule is a tiny, belated step in the right direction, but it stops far short of compelling day-trading firms to shoulder their moral responsibility.