Stocks rise and oil prices ease as Wall Street keeps yo-yoing because of the war with Iran

But the moves are shaky, and the S&P 500 more than halved an early jump of 1.2% within the first half hour of trading. Financial markets have swung sharply since the war began more than three weeks ago with strikes by the United States and Israel on Iran. Many of the sudden reversals in momentum have struck hour to hour as uncertainty continues to dominate about how long the war will last.

Keeping up that uncertainty on Wednesday: Iranian state television quoted an anonymous official as saying Iran rejected America’s 15-point ceasefire proposal. Iran also launched more attacks on Israel and Gulf Arab countries, including an assault that sparked a huge fire at Kuwait International Airport, while coming under attack itself. The U.S. military is deploying paratroopers and more Marines to the region.

Optimism, though, was nevertheless evident in financial markets worldwide. Stock indexes climbed more than 1% from London to Paris to Shanghai. The Nikkei 225 in Tokyo leaped 2.9%.

The price for a barrel of Brent crude fell 4.3% and dropped below $96 on hopes that a cooldown in fighting could allow oil and natural gas to flow more freely from the Persian Gulf to customers around the world. Many oil tankers are currently stuck outside the Strait of Hormuz off Iran’s coast, and the blockage has sent Brent crude to nearly $120 per barrel at times.

In the bond market, Treasury yields also eased. That could help soften the rise in rates for mortgages and other kinds of borrowing since the start of the war. That in turn could lessen the pressure on the economy.

The yield on the 10-year Treasury fell to 4.33% from 4.39% late Tuesday, though it remains well above its 3.97% level from just before the war.

Even gold, which has been one of the investment world’s worst losers through the war, rose. It climbed 3.5% to top $4,556 per ounce.

Gold's price had briefly gotten near $5,400 early this month. That was before Treasury yields rushed higher on worries that high oil prices would drive inflation upward and prevent the Federal Reserve from cutting interest rates. When bonds are paying more in interest, they make gold, which pays its investors nothing, less attractive in comparison.

On Wall Street, companies with big fuel bills rallied thanks to easing oil prices.

Norwegian Cruise Line Holding climbed 3.8%, and United Airlines gained 3.5%.

The stock of Arm Holdings that trades in the United States soared 15.2% after the U.K. giant unveiled a suite of chips for data centers and artificial-intelligence technology.

Robinhood Markets leaped 7.3% to help lead the U.S. market after its board authorized a program to send up to $1.5 billion to shareholders by buying back the company’s stock.

Terns Pharmaceuticals rose 5.4% after Merck said it would buy the oncology company in an all-cash deal valuing it at $6.7 billion. Merck added 2.1%.

On the losing end of Wall Street was On Holding. The Swiss company that sells On shoes slumped 6.8% after saying its CEO, Martin Hoffmann, is stepping down.

In Hong Kong, Pop Mart International Group tumbled 22.5% after the company behind the popular Labubu dolls reported explosive growth in profit and revenue, but not enough to match analysts' expectations.

AP Business Writers Chan Ho-him and Mat Ott contributed.