NEW YORK (CNN/Money) - When Wall Streeters get back to work next week, they may quickly end up longing for the lackluster trading of August: September is typically the worst month of the year for stocks.

Since 1950, if you'd bought and held stocks only in September, you'd be a pretty pitiful money manager indeed, having lost 38 percent of your money, according to data compiled by the Stock Traders Almanac. The average September loss has been 0.7 percent, while the average for all other months is a net gain of 0.7 percent.

Though October has seen some of the worst disasters in stock-market history, including the crashes of 1929 and 1987, it has been a better-than-average month most of the time, gaining, on average, 0.8 percent per year.

There have been some Septembers when stocks did just fine. Since 1950, there have been 21 positive Septembers for the S&P 500, including a winning streak that lasted from 1995 to 1998. But there have been 31 losing Septembers, including the past five in a row.

Will this year make it six?

"It's hard to see any factors that would bring this market up in September, any more strongly than it's been for some of the sessions we've had this summer," said Ozan Akcin, chief market strategist with Puglisi & Co.

June saw a healthy 1.7-percent gain in the S&P, but July saw a 3.4-percent drop, and August was on track for a mild loss, as of Tuesday afternoon.

Though Akcin and other analysts have long believed that fundamentals would dictate higher stock prices -- earnings are great, and the economy is growing -- a host of fears have confounded their hopes for a summer rally.

The cruelest month Since 1950, September has been the worst month of the year for stocks Month  Average percent change, S&P 500, 1950-2003  November  1.7  December  1.6  January  1.4  April  1.4  March  1.1  July  0.9  October  0.8  May  0.2  June  0.2  August  -0.02  February  -0.1  September  -0.7   Source:  Stock Trader's Almanac

Oil prices have stayed at or above $40 a barrel for much of the summer, at one point approaching $50. The hand-over of sovereignty in Iraq has been anything but a cure-all, and the escalating violence there has raised fears of oil-supply disruptions. Some investors are worried about the prospects for a terror attack before the November election, and others are worried that a Democratic victory in that election could cost them their recent tax cuts.

Of course, there are reasons that stocks could gain in September. Oil prices could continue their recent declines. Economic growth could rebound from a summer swoon. Traders could take heart if President Bush gains strength in the polls, as some believe business will be better with a Republican in the White House.

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But sooner or later, the business cycle will shift, and the economy and earnings growth will lose steam. In that case, stocks may have a tough time making significant gains.

"The economic numbers are driving the bus," said Paul Nolte, director of investments at Hinsdale Associates. "As long as the numbers remain kind of weak, if it doesn't look like we're getting much of a turnaround, then markets can continue to slide."

Analysts had hoped that stocks would post at least one more long-lasting rally before the bull run that began last year is officially declared dead. In fact, some had expected it to happen this summer. The fear is that, if it doesn't happen soon, if stocks keep finding reasons not to gain, they will eventually run out of time.

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"It might be too late for the party anyway," said Akcin of Puglisi & Co.

On the bright side, November is just around the bend -- that's the best month for stocks, with an average gain of 1.7 percent.

And the fundamentals of the economy and earnings might be strong enough to justify decent gains at the end of the year, no matter what history says.

"If the bull market is over, that was the shortest, wimpiest bull market I've ever seen in my life," said Jon Brorson, head of growth equities at Neuberger Berman. "Earnings are still growing, we're not looking at a recession, and it doesn't look like interest rates have to go up a lot. I think we have another run to go before this bull market's over."