U.S. stocks ended down Friday, capping a week in which erratic crude oil prices whipsawed equities, as investors gauged how the war in Iran was affecting the global oil supply.

All three major U.S. stock indexes logged daily and weekly declines.

Crude prices fluctuated before heading higher, even after U.S. President Donald Trump temporarily eased sanctions on Russian oil to assuage supply concerns.

"We've seen volatility in the energy market that rivals any two-week period in cryptocurrency history. So, it's hard to say that it's being driven by fundamentals," said Paul Nolte, senior wealth advisor & market strategist at Murphy & Sylvest in Elmhurst, Illinois.

"It's very much an emotional market, so it really doesn't make sense trying to trade, let alone invest in this market," Nolte said.

Nolte added: "You just sit back and wait for things to unfold and to settle, and that may happen over the course of a couple of weeks."

Front-month WTI crude futures settled at $98.71 per barrel, up 3.11% on the day. Brent rose 2.67% to $103.14, settling above $100 per barrel for the first time since August 2022.

Trump's vow to hit Iran "very hard over the next week," combined with reports that the conflict had spread to Lebanon, Kuwait, Iraq, the United Arab Emirates, Bahrain and Oman, has dimmed hopes of de-escalation and near-term resolution.

Trump's comments prompted Iran to tighten its grip on the Strait of Hormuz, conduit for one-fifth of the world's oil. On Thursday, the International Energy Agency said the war will cause the largest-ever disruption in global crude supply.

The Commerce Department's sharp downward revision to fourth-quarter GDP growth dominated a deluge of mostly disappointing economic indicators. Commerce slashed its previously-stated estimate in half, to 0.7%.

The Personal Consumption Expenditures report showed little movement in the U.S. Federal Reserve's preferred inflation gauge, while other data showed weakening demand for durable goods.

Despite softer economic data, the U.S. Federal Reserve was expected to leave its key interest rate unchanged at the conclusion of next week's monetary policy meeting.

With the threat of spiking oil prices further stoking inflation, the odds of a near-term rate cut are dwindling.

"Inflation remains elevated, and with the possibility of energy prices eventually moving into the pipeline, the Fed is likely to stay on hold for a longer period of time,” said Peter Cardillo, chief market economist at Spartan Capital Securities in New York.

According to preliminary data, the S&P 500 lost 40.27 points, or 0.60%, to end at 6,632.35 points, while the Nasdaq Composite lost 208.28 points, or 0.93%, to 22,103.70. The Dow Jones Industrial Average fell 117.01 points, or 0.25%, to 46,560.84.

Amid mounting concerns over credit quality, the S&P 500 financial sector fell on the week.

Design software maker Adobe fell after it was announced that longtime CEO Shantanu Narayen will leave his role once a successor is appointed, renewing worries over potential AI disruption.

Meta Platforms slid following a report that the social media behemoth has postponed the release of its artificial intelligence model "Avocado" to at least May.