Oil prices stabilized Wednesday after climbing the previous session, as investors processed President Trump's decision to extend the cease-fire with Iran. Brent crude traded at about $99 a barrel, up 0.8 percent from Tuesday's settlement, while West Texas Intermediate hovered around $90 a barrel.

Uncertainty persists despite the diplomatic extension. An adviser to Iranian Parliament Speaker Mohammad Bagher Ghalibaf dismissed the cease-fire announcement as meaningless, equating the U.S. naval blockade with bombings. Commercial vessels reported coming under attack near the Strait of Hormuz, the narrow waterway that normally carries as much as one-fifth of the world's oil supply.

U.S. stock futures pointed to a strong open, with S&P 500 futures rising more than 0.6 percent. Asian markets were mixed—Hong Kong's Hang Seng fell more than 1 percent while Taiwan's Sensex gained about 1 percent. European markets were largely flat.

Gasoline held steady at a national average of $4.02 a gallon, down from $4.17 earlier in April but still up 35 percent since the war began. Diesel rose to $5.49, a 46 percent increase.