A sharp sell-off swept US financial markets on Friday, October 16, 2026, as technology shares tumbled while oil prices climbed above $110 per barrel.
The drop reflected mounting worries over inflation, borrowing costs, and whether heavy spending on artificial intelligence will pay off.
The Nasdaq 100 fell 2.5%, leaving the index roughly 7% below its latest record high set the previous week, according to market figures reported by NBC News.
The S&P 500 slipped 1%, and the Russell 2000 dropped 1.6%.
The Philadelphia semiconductor index lost 3.8%, its eighth straight session of declines and its longest losing streak since 2008.
The broader technology retreat erased an estimated $1 trillion in market wealth.
Oil Prices Add Pressure on Rates
Brent crude briefly exceeded $110 per barrel shortly after 2:30 p. m.
Eastern time, its highest level since May.
It closed the week at $109.86 per barrel, the highest closing price since May 19.
US West Texas Intermediate crude gained 3.5% on Friday to settle at $101.41 per barrel, crossing $100 for the first time since September.
Higher energy prices have fueled concerns that the Federal Reserve could raise interest rates again this year.
The central bank raised rates by 0.25% in September to fight inflation that had climbed alongside higher oil and gasoline prices.
Diesel futures also advanced more than 1% on Friday, extending a rise that has outpaced regular gasoline in recent months.
The increase in global fuel costs began this spring after US and Israeli attacks on Iran in late February triggered the closure of the Strait of Hormuz.
More recently, intensifying Russia-Ukraine hostilities have added pressure to diesel supplies.
Russia, traditionally one of the world's largest diesel exporters, has lost refining capacity following Ukrainian attacks on its energy infrastructure.
Another Russian refinery suspended some crude oil operations on Friday.
Russia's Defense Ministry said Ukraine had "attempted a massive attack on the Ryazan oil refinery." Russian forces have also targeted energy infrastructure in Ukraine.
Expanding global diesel production remains difficult because refineries in the United States and Europe are already operating near maximum capacity.
The supply constraints have complicated efforts to replenish inventories and ease prices.
President Donald Trump has focused on diesel costs because of their contribution to inflation, a major issue for voters ahead of the November 3 midterm elections.
His efforts to lower prices have not produced a significant decline.
A proposed arrangement with Russian President Vladimir Putin has also yet to deliver identifiable Russian diesel to the global market as of Friday.
Some American lawmakers have introduced legislation to block the proposed Russian diesel arrangement.
The bill has little chance of passing the Republican-controlled House, although polling cited in the report suggests Republicans could lose their majority after the November elections.
Mason Mendez, a global real assets analyst at Wells Fargo, said the legislation reflects increasing uncertainty about the proposed agreement.
"Investors also remain concerned about further military escalation in the Middle East, as attacks on commercial shipping and regional infrastructure have increased in recent weeks," Mendez said.
Mendez also warned that energy prices could remain elevated as global inventories need replenishment.
"Looking into 2027, the need to rebuild depleted global inventories could create an additional source of demand and keep energy prices elevated for longer," he said.
AI Spending Under Scrutiny
Investors are questioning whether major technology companies can generate sufficient returns from their substantial AI spending while financing costs remain high.
Companies have borrowed and committed hundreds of billions of dollars to develop AI systems and expand data center capacity.
Two of the Nasdaq 100's worst-performing stocks on Friday were data center operators Nebius and CoreWeave.
CoreWeave shares have fallen more than 25% over the previous month, according to NBC News.
The companies are among dozens of businesses that have borrowed billions of dollars at high interest rates to accelerate expansion.
Market analyst Ed Yardeni lowered his year-end S&P 500 target to 7,900 from 8,400 on Thursday, citing increased investor caution toward AI-related investments and continuing concerns about inflation and higher interest rates.
