The mini-stock market crash of Friday, Oct. 13, 1989, which drove the Dow Jones industrial average down 191 points in 90 minutes, was fueled by the combined selling of program traders in New York and futures speculators in Chicago, the Securities and Exchange Commission said yesterday.

In a 267-page report on the October market upheaval, the SEC said it found an unusual amount of futures selling by speculators in Chicago and suggested that the relatively low margins, or down payments, required by the Chicago markets may have accounted for the increased speculation.

The SEC, which has criticized Chicago's low margin levels before, warned that the turbulence seen in October could return.

"Given current market and regulatory structures, there can be no assurance that the extraordinary volatility of Oct. 13 and 16 will not be repeated or surpassed in the future," the SEC said.

On Monday, Oct. 16, the Dow dropped an additional 63 points before rallying and closing with a gain of 88 points for the day.

In an earlier report on the October events, the Commodity Futures Trading Commission (CFTC) appeared to find nothing amiss with the way the markets functioned nor any cause for alarm.

The SEC's Oct. 13 study was published the same day Bush administration officials went to Capitol Hill to debate legislation that would give the SEC more control over stock index futures, which trade in the Chicago futures markets.

A futures contract on a stock index, or a basket of stocks, is an investment generally used by institutional investors to hedge against price changes in the actual stocks.

In computerized program trading, institutional investors are able to profit from tiny price differences between stocks and stock indexes.

Treasury Undersecretary Robert Glauber, representing Treasury Secretary Nicholas F. Brady, and SEC Chairman Richard C. Breeden want to strip the authority to regulate stock index futures from the CFTC and give it to the SEC.

The administration plan was reluctantly endorsed by Federal Reserve Chairman Alan Greenspan, who said he was more concerned with what might happen in the future than what has happened in the past.

"What we are endeavoring to do is to visualize the things that can go wrong and fend them off," he said.

CFTC Chairman Wendy Gramm vigorously opposed the plan.

After the hearing, Breeden told reporters that if Congress did not act on the administration proposal this year, he might consider supporting a full merger of the SEC and CFTC.

One of the major arguments for giving the SEC control over stock index futures is that the stocks and futures are part of "one market," even though they trade in two cities and are controlled by two agencies.

Asked by reporters whether the SEC report supported the administration's call for a single regulator, Breeden said:

"It certainly proves the interrelationship of these markets. Selling pressures are immediately transferred from one market to the other, reflecting the fact that the same thing is being sold in both markets -- the {Standard & Poor's} 500 stocks directly in New York, the S&P 500 stocks in the futures market through the device of a futures contract, essentially wrapping the 500 stocks in cellophane and selling them as a package."

A single economic unit, Breeden said, should have a single regulator.

The Bush administration bill, as outlined yesterday by Glauber at the House subcommittee on telecommunications and finance, also would:

Change the Commodity Exchange Act in a way that would end the conflict over which agency controls products that are a mixture of stocks and futures.

Enhance the SEC's ability to prevent fraud and manipulation in the trading of both stocks and stock index futures across both markets.

Require the SEC to report to Congress in 18 months on other changes needed to regulate stocks, stock options and stock index futures.