By Joe Wallace
U.S. stock futures wobbled Friday, signaling that parts of the market may extend losses after a burst of volatility in highflying technology stocks prompted the biggest tumble in the S&P 500 in almost three months.
Futures tied to the S&P 500 wavered between gains and losses. The broad market gauge on Thursday dropped 3.5% in its biggest retreat since June 11, leaving the S&P 500 on track for its first weekly loss in six weeks.
Nasdaq Composite futures slid 1%, suggesting the tech-heavy index could come under further pressure after tumbling 5% on Thursday. The gauge's one-day point decline was its largest in almost six months.
The tech sector's selloff was driven by a retreat in many of the companies that drove the rally in U.S. stocks in recent months. A record $180 billion was erased from Apple Inc.'s market valuation on Thursday after the stock dropped 8%. That is the most that any American company has ever lost in a single day. Despite the rout, Apple's stock is up 65% this year. The shares ticked down 1.8% in premarket trading.
Investors are gauging an incomplete economic recovery and reassessing valuations that had decoupled from corporate fundamentals, according to Samy Chaar, chief economist at Lombard Odier.
"In the past few weeks, there's been a big trade on newer technology that wasn't built on a lot," Mr. Chaar said. "We saw the worst of the [economic] shock. But what I would add to that is that we've seen the best of the recovery."
The Cboe Volatility Index, a gauge of expected swings in the S&P 500, slipped 1.3 points. On Thursday, the so-called Vix jumped seven points, its biggest one-day advance since June.
The bout of volatility is unlikely to be the start of a downtrend, in part because institutional investors still have further room to boost their exposure to stocks, said Sophie Huynh, cross-asset strategist at Société Générale. "For now I think the selloff could be fairly limited," she said.
Attention is likely to focus sharply on the monthly report on the U.S. labor market, due at 8:30 a.m. ET, for evidence on the pace of the economic rebound. Hiring likely eased in August from a faster pace earlier this summer, a sign the economy is settling in for a slow recovery from the shock of the coronavirus pandemic.
Economists expect employers to have added about 1.3 million jobs in August, a solid monthly payroll gain but the smallest in four months. State reopenings helped boost employment by a combined 7.5 million payrolls in May and June before hiring growth slowed in July.
"It's a partial and incomplete recovery so far," said Agnès Belaisch, chief European strategist at the Barings Investment Institute. She is watching to see if the so-called participation rate rises, which would indicate Americans who had stopped looking for work are re-entering the workforce.
The yield on 10-year Treasury notes ticked up to 0.646%, from 0.621% Thursday, ahead of the jobs report. Yields rise as bond prices fall. The WSJ Dollar Index, which tracks the U.S. currency against a basket of others, was steady.
Prices for Brent crude rose 0.7% to $44.35 a barrel. That still puts the international oil benchmark on course to lose 3.5% this week. That would be its biggest weekly decline since mid-June. A swift recovery in fuel consumption by U.S. drivers is petering out, posing new challenges to the oil market, economy and energy industry.
International markets were mixed. The Stoxx Europe 600 advanced 0.1%, led by shares in banks and travel-and-leisure companies.
In Asia, Japan's Nikkei 225 closed down 1.1%, South Korea's Kospi Composite lost 1.2% and China's Shanghai Composite fell 0.9%. Australia's S&P/ASX 200 fell nearly 3.1%, in its worst session since the start of May.
The pullback in stocks bears similarities to an earlier retrenchment in June, said Eli Lee, head of investment strategy at Bank of Singapore. He doesn't see scope for a deep correction.
"In the longer term, low interest rates and the gradual recovery in the global economy will be supportive for risk assets," said Mr. Lee.
--Chong Koh Ping contributed to this article.
Write to Joe Wallace at Joe.Wallace@wsj.com