San Francisco Frontiers - Oil surges, stocks sink on jitters over US plans in Iran war

But the cost surge eased slightly after US President Donald Trump ruled out hitting Iran before the November vote, saying Washington was holding "productive discussions" with Tehran.

Brent North Sea crude, the international benchmark, rallied to as high as $105.88 a barrel before retreating to $104.28.

The main US contract, West Texas Intermediate, reached as high as $93.20 per barrel but eventually closed at $91.49.

The Atlantic magazine reported that the White House had asked the Pentagon to draw up options for hitting sites in Iran ahead of midterms on November 3.

But with Trump's Republican party standing a chance of losing both houses of Congress, an escalation in the US-Iran conflict could put even more pressure on the president. Already, Americans are battling record-high diesel prices.

Following the surge in energy costs, Trump wrote on his Truth Social platform Thursday that "we will not be attacking Iran at any time prior to the Midterm Elections."

Still, oil markets are reacting not only to nervousness over Trump's plans but to "increased Iranian attacks on traffic through the Strait of Hormuz," said Andy Lipow of Lipow Oil Associates.

Another concern is "Hurricane Isaias coming through the Gulf of Mexico and shutting in a significant amount of oil production," he said.

- Pressure on yields -

Meanwhile Yemen's Houthis took aim at Riyadh airport with missiles and warned staff at oil facilities in Saudi Arabia to leave to avoid being targeted as hostilities escalate.

"The renewed rise in oil prices is intensifying inflation concerns and adding to upward pressure on bond yields," said Forex.com analyst Fawad Razaqzada.

Yields on government bonds have recently touched highs unseen in more than 20 years as investors fear sustained inflation will force central banks to raise interest rates, thus slowing economic growth and hitting equity market valuations.

The surge in oil prices weighed on stock markets, with Wall Street's main indexes mostly closing lower.

Europe's main markets finished the day in the red, including London, although higher oil prices benefited energy majors.

Asia's leading stock markets tracked losses Wednesday on Wall Street, where technology firms pulled back from recent gains.

Shares in Samsung slid as the South Korean titan forecast a huge increase in quarterly profit that nonetheless failed to meet market expectations.

On Wall Street, shares in SpaceX slid 4.2 percent following a Financial Times report that Elon Musk's firm is aiming to raise $40 billion in bank loans and debt to further its purchases of AI chips from Nvidia.

A Financial Times report that OpenAI is bringing in about $20 billion less in annualized revenue than investors were led to believe also weighed on markets.

"It raises the question about all AI companies," said Adam Sarhan of 50 Park Investments. "If OpenAI is missing revenue estimates, what does that mean for the other AI companies?"

- Key figures at around 2030 GMT -

Brent North Sea Crude: UP 4.1 percent at $104.28 per barrel

West Texas Intermediate: UP 3.6 percent at $91.49 per barrel

New York - Dow: UP 0.1 percent at 51,231.64 points (close)

New York - S&P 500: DOWN 0.5 percent at 7,765.36 (close)

New York - Nasdaq Composite: DOWN 1.3 percent at 27,193.34 (close)

London - FTSE 100: DOWN 0.2 percent at 10,441.60 (close)

Paris - CAC 40: DOWN 0.5 percent at 7,729.69 (close)

Frankfurt - DAX: DOWN 1.2 percent at 24,806.97 (close)

Tokyo - Nikkei 225: DOWN 1.4 percent at 69,042.11 (close)

Hong Kong - Hang Seng Index: DOWN 1.4 percent at 23,785.79 (close)

Shanghai - Composite: DOWN 0.8 percent at 3,811.90 (close)

Euro/dollar: UP at $1.1213 from $1.1194 on Wednesday

Pound/dollar: UP at $1.3228 from $1.3210

Dollar/yen: DOWN at 157.92 yen from 158.07 yen

Euro/pound: UP at 84.77 pence from 84.74 pence

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G.Collins--SFF