Oil prices jumped and early trading on Wall Street was mixed Monday after the U.S. carried out airstrikes and Iran retaliated.
Futures for the S&P 500 fell 0.3%, futures for the Dow Jones Industrial Average were unchanged and Nasdaq futures tumbled 0.8%.
Chip and memory companies were dragging indices down, with SanDisk, Western Digital and Micron all falling close to 5% in premarket.
Energy producers ExxonMobil, ConocoPhillips and Chevron all gained around 1% before the opening bell as fighting in the Middle East pushed oil prices higher.
Brent crude, the international standard, climbed as much as nearly 5% early Monday before falling back. As of midday in Europe, it was up 3.4%, or $2.58, at $77.72 per barrel, while U.S. benchmark crude added 3.5%, or $2.48, to $72.92 per barrel.
Prices for both types of crude oil recently had slipped back to around the levels they were at before the war with Iran began after the two sides set an interim agreement on ending the conflict and ships resumed transporting oil through the Strait of Hormuz.
However, the United States launched several waves of strikes on Iran into Monday morning over an Iranian attack on a container ship in the strait that set it ablaze and left a crew member missing over the weekend. Iran retaliated by targeting countries across the Middle East.
This week will bring earnings reports from many of the biggest U.S. banks, including Bank of America, Citigroup, JPMorgan Chase, Goldman Sachs and Wells Fargo on Tuesday alone.
Meanwhile, worries about how continued fighting with Iran will affect the global flow of crude are clouding the outlook both for energy costs and overall inflation.
High bond yields have been weighing on financial markets worldwide since more expensive oil and high inflation could push the Federal Reserve and other central banks to raise interest rates.
Higher rates can keep a lid on inflation, but they also slow the economy and hurt prices for all kinds of investments.
Elsewhere, at midday in Europe, Germany's DAX added 0.2%, as did the CAC 40 in Paris. Britain's FTSE 100 was unchanged.
In Asian trading, Tokyo's Nikkei 225 index lost 1.9% to 67,242.73, while in Seoul, the Kospi declined 9% to 6,806.93. It's now at its lowest level since early May.
Shares in South Korean memory chipmaker SK Hynix, which soared 13% in their debut Friday on Wall Street, slumped 15.4% in Seoul. Its bigger rival Samsung Electronics sank 10.7%.
Hong Kong's Hang Seng edged 0.2% higher, to 24,212.36, and the Shanghai Composite index shed 2.1% to 3,913.79.
In Australia, the S&P/ASX 200 was nearly unchanged at 8,808.50.