On the 20th (local time), all three major U.S. stock indexes in New York fell.
The Dow Jones Industrial Average ended at 45,577.47, down 443.96 points, or 0.96%, from the previous session.
The Standard & Poor's (S&P) 500 index fell 100.01 points, or 1.51%, to 6,506.48 from the previous session, and the tech-heavy Nasdaq composite closed at 21,647.61, down 443.08 points, or 2.01%.
New York stocks extended losses for a fourth straight week, and the Dow and Nasdaq are on the verge of entering a correction phase.
The move appeared driven by growing risk aversion amid fears that the Middle East war will expand and drag on.
As Iran and Israel traded airstrikes overnight, reports emerged that the United States would deploy additional troops to the Middle East.
Reuters, citing U.S. officials, reported that the U.S. military decided to send thousands more Marines and Navy personnel to the Middle East. There was speculation the forces, positioned along the coast, could be included in an operation to control the Strait of Hormuz.
CBS reported that the United States is making full-fledged preparations in case ground troops are sent into Iran.
Near the close, comments also emerged from President Trump that he does not want a cease-fire with Iran.
With passage through the Strait of Hormuz—used by about 20% of global crude shipments—blocked, concerns over supply disruptions mounted and international oil prices surged.
Brent crude, the international benchmark, topped $112 per barrel. May delivery Brent futures finished at $112.19, up 3.3% from the previous session.
April delivery West Texas Intermediate (WTI) futures settled at $98.32 per Barrel, up 2.3% from the previous session.
Treasury yields rose (prices fell) as inflation fears grew on higher oil prices. The move reflected rising expectations that the Federal Reserve (Fed) may not cut its benchmark rate at all this year due to inflationary pressures.
Some in the market are increasingly betting that the Fed could opt for a rate hike, not a cut, at its next decision.