By Aaron Kuriloff and Corrie Driebusch

The S&P 500 recorded its longest stretch of declines since the financial crisis, as investors dialed back on risk in the run-up to next week's U.S. presidential election.

Tightening polls and falling oil prices have overwhelmed recent data signaling growth in the U.S. economy, pushing the index into an eight-day slide.

The S&P 500 has fallen 2.9% since Oct. 25, a protracted decline that is much milder than the 23% drop in the index's previous eight-session losing streak in October 2008, which included the signing of the $700 billion financial-rescue package, just weeks after the collapse of Lehman Brothers Holdings.

This year's slump is also a far cry from the Brexit selloff, when the index slid 5.3% over two sessions following the U.K.'s vote to leave the European Union in June.

None of the most recent eight sessions included a decline greater than 1%, and Oct. 31's fall was less than a point in the index. Some investors and analysts said the slump reflected caution, rather than fear, especially after investors got burned by the surprise outcome of the Brexit vote and the sharp selloff that followed.

"There's obviously a lot of angst going into the election," said Erik Davidson, chief investment officer at Wells Fargo Private Bank. "The lessons of the Brexit vote are still pretty recent, so I think people are a little cautious about what the markets have priced in and what could happen."

On Thursday, the S&P 500 fell 9.28 points, or 0.4%, to 2088.66, while the Nasdaq Composite Index slipped 47.16 points, or 0.9%, to 5058.41, as a slide in tech shares pressured both indexes. The Dow Jones Industrial Average dropped 28.97 points, or 0.2%, to 17930.67.

If the S&P 500 falls again, that would mark its first nine-session slide since 1980. Friday is set to include updated unemployment data from the Labor Department, with economists expecting the jobs report to show the U.S. economy added 173,000 new jobs last month, up from 156,000 a month earlier.

A strong report could bolster the Federal Reserve's case for raising interest rates in December. The Fed on Wednesday left interest rates unchanged, as expected, while sending new hints it expects to raise rates this year.

The recent declines come after a strong third quarter for stocks, with the S&P 500 up 6.1% for the year as of Sept. 30 on a rebound in riskier shares like financials and technology. The index is now up 2.2% year to date.

Shares of Facebook on Thursday tumbled 5.6%, to $120, its biggest fall since February, after the social-media company cautioned of slowing advertising growth late Wednesday. Facebook remains up 15% in 2016 and was the biggest contributor to the S&P 500's gains through the end of October, according to S&P Dow Jones Indices.

Many investors had hoped that improving earnings would provide the next boost to stocks after major indexes hit records this summer. Any sign that sales and earnings could be weakening can be unnerving, as stock prices remain elevated relative to their past 12 months of earnings.

The S&P 500 trades at about 19.2 times the past 12 months of earnings, above its 10-year average of 15.7, according to FactSet. Some investors have rationalized buying stocks at these levels because bond yields are low. Others, however, are waiting on earnings growth to return. Earnings in the S&P500 have declined for five consecutive quarters, according to FactSet.

With about 400 companies in the S&P 500 having reported third-quarter results, earnings are on track to increase 2.6% from a year earlier, according to FactSet.

"Earnings and economic data are doing exactly what a lot of people expected, which is to improve," said Jamie Cox, managing director at Harris Financial Group, which manages about $697 million.

The Commerce Department said last week that U.S. gross domestic product advanced at a 2.9% inflation-adjusted annual rate in the third quarter, the strongest reading in two years. But solid earnings and economic data haven't been enough to buoy stocks.

The selling in stocks mirrored a broad decline in risk appetite in recent sessions. U.S. crude prices fell Thursday for a fifth straight session, losing 10% over that period in oil's worst stretch since Feb. 11, when prices hit a 2016 low. On Thursday, crude for December delivery lost 1.5%, to $44.66 a barrel.

U.S. government bonds have rallied this week as investors sought haven assets, although prices retreated Thursday, with the yield on the 10-year Treasury note settling at 1.811%, down from 1.847% at the end of last week. Bond yields move inversely to prices. Gold, another asset perceived as safe, has risen 2.1% since Friday.

In Europe, the Stoxx Europe 600 rose less than 0.1%, ending eight consecutive sessions of losses.

--Daniel Huang contributed to this article.

Write to Aaron Kuriloff at aaron.kuriloff@wsj.com and Corrie Driebusch at corrie.driebusch@wsj.com

(END) Dow Jones Newswires

November 03, 2016 19:08 ET (23:08 GMT)

Copyright (c) 2016 Dow Jones & Company, Inc.