New regulations likely as U.S. probes big stock dive

President Barack Obama said on Friday that regulators would look for ways to prevent a repeat of Thursday's mysterious stock market meltdown, adding to expectations the U.S. government will make new regulations to curb runaway computer trading.

More than a day after a nearly 1,000-point drop in the Dow, the government had not publicly pinpointed the reasons.

Growing concern about the Greek debt crisis, exacerbated by a spike in the Japanese yen, may have caused computerized trading programs to dump U.S. stocks. Initial theories had focused on an individual trader erroneously entering an order, known as fat finger on Wall Street.

The regulatory authorities are evaluating this closely with a concern for protecting investors and preventing this from happening again, said Obama, who called the selloff unusual market activity when he spoke to reporters.

More than 50 people were working on the investigation into the night on Friday -- some who have slept for only two hours since Thursday's plunge -- but regulators still do not know whether it started outside or within equity markets, a government source close to the probe told Reuters.

Politico, a news organization that covers U.S. politics and government, said regulators were eyeing a series of high-volume trades in S&P futures in Chicago as the trigger.

Whatever the cause, the biggest-ever intraday point drop in the Dow stoked outrage among investors and politicians already up in arms over Wall Street's role in the global recession.

We should expect the regulators to use every tool available to them to lower the speed limit on financial markets, and especially on banks, Mohamed El-Erian, chief executive of Pacific Investment Management Co, told Reuters Insider. You will see regulation, taxation and enforcement all being used.

Two Democratic senators called for an amendment to the financial reform bill, asking U.S. regulators to report on the causes of Thursday's market plunge and whether circuit breakers are needed for computer-driven trading.

The selloff came as the U.S. Senate debated Obama's proposed crackdown which, like recent civil fraud allegations against Goldman Sachs Group Inc, could fuel enthusiasm for the legislation.

Indeed, Senators Ted Kaufman and Mark Warner asked Christopher Dodd, chairman of the Senate Banking Committee, to add their amendment to the bill, according to a copy of a letter obtained by Reuters.

A temporary $1 trillion drop in market value is an unacceptable consequence of a software glitch, Kaufman and Warner said in the letter.

European Union market supervisors agreed on Friday to intensify monitoring due to wild stock and derivative swings.

The Dow industrials finished down 3.2 percent on Thursday. The index lost 1.3 percent on Friday but there was no sign of the kind of selling that wracked the market on Thursday.

It's a day that no one in the markets should be proud of, said William O'Brien, chief executive of Direct Edge, a trading venue operator that handles more than 10 percent of all U.S. stock trading. While a lot of regulation worked to mitigate the risks that became really evident yesterday, there's clearly more that we can do.

While the reasons behind the market swoon remained unclear, one senior portfolio manager at a large corporate pension plan speculated the move could have been set off by an algorithm responding to a spike in the Japanese yen, first against the euro, then against the dollar.

That in turn may have touched off computer orders to dump large amounts of stock more or less instantaneously, the portfolio manager said.

That set off a nuclear process of one order banging into the next and exploding, he said. At the end of the day, the fault lies with poor programing and lack of intelligent human override.

CIRCUIT BREAKER SOUGHT

The Securities and Exchange Commission and Commodities Futures Trading Commission reiterated that they were examining the reasons behind the selloff, and scrutinizing the extent to which disparate trading conventions and rules across various markets may have contributed to the spike in volatility.

There are two issues for regulators and exchanges. One is to ensure that the same kind of rapid selloff does not happen again; the other is to determine if someone in the market was trying to take advantage of the situation.

Even before Thursday's meltdown, the SEC had been probing high-frequency trading and the structure of the mostly electronic marketplace, which has undergone a high-tech transformation over the past decade.

High-frequency trading, where firms use lightning-quick algorithms to capitalize on tiny market imbalances, accounts for an estimated 60 percent of all volumes. Investors and exchanges have come to rely on those short-term traders to keep markets flowing.

There was no shortage of proposals to avoid a repeat, and leading exchanges sniped among themselves over where the blame lay and what the best solution was.

Nasdaq OMX Group will push for a marketwide circuit breaker based on individual stocks, Chief Executive Robert Greifeld said. Duncan Niederauer, chief executive of NYSE parent NYSE Euronext, touted his exchange's use of a lever that slows down floor trading.

The New York Stock Exchange's use of its mini circuit breaker on Thursday afternoon was akin to abandoning its listed stocks, Greifeld said.

That signal is a negative signal that there is something wrong with (NYSE's) stocks. Instead of standing behind it, they basically walked away from that, Greifeld said on CNBC.

Niederauer defended the use of the so-called Liquidity Refreshment Point, which kicks in at pre-established times based on market activity.

We're simply slowing down the race car when we think it's dangerous, he told CNBC.

CANCELED TRADES

The Nasdaq Stock Market early on Friday widened its list of stocks facing canceled trades, and the focus turned to derivatives and regulators.

Trades that took place during the worst of the meltdown have been canceled for more than 250 stocks, Nasdaq OMX said, adding to the long list of busted transactions on NYSE Euronext's Arca, other exchanges and trading venues.

A record number of options contracts traded on Thursday.

A handful of high-frequency firms told Reuters they had temporarily stopped trading on Thursday, citing the heavy market plunge and uncertainty over which trades would be canceled.

We were concerned there would be trade breaks, and as a result, we would be left with an unpredictable position at the end of the day, said Manoj Narang, CEO of Tradeworx, a New Jersey-based hedge fund that also runs a high-frequency unit.

(Additional reporting by Ross Kerber, Al Yoon, Dan Wilchins, Pedro Nicolaci da Costa, Matthew Goldstein, Karey Wutkowski, Margaret Chadbourn, Kevin Drawbaugh, Donna Smith, David Lawder, Christopher Doering and Roberta Rampton: Writing by Christian Plumb. Editing by Robert MacMillan and Peter Cooney)