NEW YORK — Oil prices and stock markets worldwide swung through a shaky Monday with uncertainty about what will happen with the Iran war.

The S&P 500 swiveled between gains and losses before finishing with a dip of 0.1%, its second loss since setting an all-time high last week. The Dow Jones Industrial Average added 159 points, or 0.3%, and the Nasdaq composite fell 0.5% after both indexes likewise yo-yoed.

Stock prices moved in the opposite direction of oil prices, which have been twitchy because of uncertainty about how long the Iran war will keep the Strait of Hormuz closed and prevent oil tankers from delivering crude. The price for a barrel of Brent crude oil, the international standard, went from a high of $112 overnight to below $107 in the morning before turning back higher.

After settling at $112.10 per barrel, Brent’s price then fell back below $109 after President Donald Trump said late in the day that he would hold off on a military attack on Iran planned for Tuesday, at the request of allies in the region. That kept alive hopes that a deal to open the Strait of Hormuz may still be possible.

The moves for oil prices have helped make the world’s bond markets the center of the action recently. Climbing yields there have cranked up the pressure on economies and stock markets worldwide.