NEW YORK, July 19 U.S. stocks extended their slump on Friday as lingering chaos related to a global technical outage caused by a software glitch added uncertainty to an already-anxious market.

The far-reaching tech outage disrupted operations across multiple industries including airlines, banking and healthcare after the glitch in cybersecurity firm Crowdstrike's (CRWD.O), opens new tab software caused Microsoft's (MSFT.O), opens new tab Windows operating system to crash.

While the flaw was identified and fixes deployed, technical issues continue to affect some services.

Crowdstrike shares slid 11.1%, while rival cybersecurity firms Palo Alto Networks (PANW.O), opens new tab and SentinelOne (S.N), opens new tab advanced 2.2% and 7.8%, respectively.

All three major U.S. stock indexes ended in negative territory, with the Dow Jones Industrial average suffering the worst of it.

On a weekly basis, both the Nasdaq and the S&P 500 logged their worst week since April, while the Dow, having reached a series of all-time closing highs earlier in the week, posted a Friday-to-Friday gain.

"This tech outage adds some uncertainty and puts pressure on the overall Nasdaq," said Robert Pavlik, senior portfolio manager at Dakota Wealth in Fairfield, Connecticut. "But it won’t have much of an overall impact. Some buying will be delayed. Not only is it a summer Friday but because of the outage (investors) are in wait-and-see mode."

"They're sitting on the sidelines," Pavlik added. "That's what happens to the stock market when volatility rules the day."

The CBOE Market volatility index (.VIX), opens new tab, considered a gauge of investor anxiety, touched its highest level since late April.

The smallcap Russell 2000 (.RUT), opens new tab - a beneficiary of a recent pivot away from megacap growth stocks - ended modestly lower.

Nvidia shares (NVDA.O), opens new tab led a sell-off in chips. The Philadelphia SE Semiconductor index (.SOX), opens new tab underperformed the broader market, falling 3.1%.

Elsewhere, Federal Reserve Bank of New York President John Williams reiterated the central bank's commitment to bringing inflation down to its 2% target.

Financial markets have priced in a 93.5% likelihood that the Fed will enter a rate-cutting phase at the conclusion of its September meeting, according to CME's FedWatch tool.

The Dow Jones Industrial Average (.DJI), opens new tab fell 377.49 points, or 0.93%, to 40,287.53, the S&P 500 (.SPX), opens new tab lost 39.59 points, or 0.71%, to 5,505 and the Nasdaq Composite (.IXIC), opens new tab dropped 144.28 points, or 0.81%, to 17,726.94.

Among the 11 major sectors of the S&P 500, energy shares (.SPNY), opens new tab fell the most, while healthcare (.SPXBK), opens new tab and utilities (.SPLRCU), opens new tab were the only gainers.

Second-quarter earnings season ended its first full week, with 70 of the companies in the S&P 500 having reported. Of those, 83% have beaten consensus, according to LSEG.

Analysts now see aggregate year-on-year S&P 500 earnings growth of 11.1%, an improvement over the 10.6% estimate as of July 1.

Next week, a swath of high-profile results is expected from Tesla (TSLA.O), opens new tab, Alphabet (GOOGL.O), opens new tab, IBM (IBM.N), opens new tab, General Motors (GM.N), opens new tab, Ford (F.N), opens new tab and a host of other companies.

"It's early in earns season, but things have been impressive," said Ryan Detrick, chief market strategist at Carson Group in Omaha, Nebraska. "But the big boys are starting to report next week and what we want to hear is how strong the consumer is and what's the outlook for future economic growth."

Eli Lilly (LLY.N), opens new tab advanced 1.0% after China approved its weight-loss drug tirzepatide, while Intuitive Surgical (ISRG.O), opens new tab jumped 9.4% after a second-quarter results beat.

Travelers (TRV.N), opens new tab tumbled 7.8% on lower-than-expected growth in net written premiums.

Netflix (NFLX.O), opens new tab fell 1.5% in choppy trading after the streaming giant cautioned third-quarter subscriber additions would be lower than a year earlier.

Oilfield services provider SLB (SLB.N), opens new tab rose 1.9% after strong second-quarter profit.

Declining issues outnumbered advancing ones on the NYSE by a 2.11-to-1 ratio; on Nasdaq, a 1.91-to-1 ratio favored decliners.

The S&P 500 posted 27 new 52-week highs and 4 new lows; the Nasdaq Composite recorded 50 new highs and 99 new lows.

Volume on U.S. exchanges was 10.54 billion shares, compared with the 11.72 billion average for the full session over the last 20 trading days.