Updates with closing U.S. market levels

By Caroline Valetkevitch

NEW YORK, June 18 (Reuters) - Major stock indexes climbed on Thursday as semiconductor shares jumped, while Brent oil touched its lowest level in weeks before finishing slightly higher.

An interim deal between the United States and Iran to end the Middle East war took effect, and oil tankers sailed through the Strait of Hormuz, pointing to a resumption of long restricted energy flows.

U.S. Vice President JD Vance, however, warned Israel against further attacks on Iran-backed Hezbollah in Lebanon, raising doubts about the durability of the U.S.-Iran ceasefire agreement.

Brent crude futures LCOc1 gained 30 cents, or 0.38%, to settle at $79.85 a barrel after sliding as low as $76.54 earlier in the session. U.S. West Texas Intermediate CLc1 fell 19 cents or 0.25% to finish at $76.60 a barrel.

Europe is more vulnerable to an increase in inflation from higher oil prices than the United States.

The U.S. dollar index hit a one-year high after a hawkish tilt by the Federal Reserve on Wednesday raised bets on rate increases this year.

The Nasdaq gained 1.9% and led gains on Wall Street, while the Philadelphia semiconductor index .SOX rose 6.4%.

U.S. President Donald Trump said iPhone maker Apple AAPL.O had agreed to work with Intel INTC.O to design and manufacture its chips in the U.S.. Intel shares jumped 10.6%.

Peter Cardillo, chief market economist at Spartan Capital Securities in New York, noted the rebound in stocks from a day earlier.

"The reason for the optimism was Trump and the president of Iran signed the memorandum and oil prices fell," he said, adding: "There is enthusiasm that after 60 days a more solid deal will come to fruition and, by that time, hopefully the low supply factor in the oil market will be reversed."

DOLLAR FIRM

The Dow Jones Industrial Average .DJI rose 72.15 points, or 0.14%, to 51,564.70, the S&P 500 .SPX rose 80.48 points, or 1.08%, to 7,500.58 and the Nasdaq Composite .IXIC rose 496.28 points, or 1.91%, to 26,517.93.

With the market closed on Friday for the Juneteenth holiday marking the emancipation of enslaved Black Americans, the S&P 500 showed a 0.93% weekly gain compared with the Nasdaq's 2.43% advance and the Dow's 0.71% increase.

MSCI's gauge of stocks across the globe .MIWD00000PUS rose 6.48 points, or 0.58%, to 1,127.60.

The pan-European STOXX 600 .STOXX index fell 0.34%.

In foreign exchange, the dollar index =USD, which measures the greenback against a basket of currencies including the yen, euro and sterling, rose 0.45% to 100.80, the highest level since May 2025. It surged 0.85% the previous session, its biggest single-day jump in over three months.

The U.S. central bank on Wednesday held rates steady in a 3.50% to 3.75% range as Kevin Warsh took charge with a sweeping policy review. The Fed funds futures market is pricing in 68% odds of a rate hike by September, LSEG data shows.

The Japanese yen JPY= weakened as far as 161.45 per dollar, its lowest since July 2024, wiping out gains made after Tokyo's intervention on April 30. A break above the currency pair's 2024 high of 161.99 would send the yen to its weakest level since 1986.

Sterling GBP= fell 0.62% to $1.3206 after the Bank of England left interest rates unchanged.

U.S. Treasury yields fell after rising the day before. The two-year yield US2YT=RR, the most sensitive to Fed rate-change expectations, was down 1 basis point on Thursday at 4.153%, after rising as high as 4.207% on Wednesday. The 10-year yield US10YT=RR was down 3 basis points at 4.437%.

U.S. gold futures GCcv1 fell 3.1% to settle at $4,245.9.