The price for a barrel of Brent crude oil, the international standard, climbed 5.6% to settle at $95.48 on worries that Iran could keep petroleum pent up in the Persian Gulf if it continues to block tankers from exiting the Strait of Hormuz.

Wall Street saw a sharp turnaround from Friday's rally, when stocks soared and oil prices tumbled after Iran briefly reopened the Strait to commercial traffic. Enthusiasm faded quickly as Iran closed it again Saturday, responding to the U.S. blockade of its ports. A key ceasefire deadline looms Tuesday at 8 p.m. ET (early Wednesday in Tehran).

Norwegian Cruise Line Holdings dropped 3.5% and Royal Caribbean lost 1.1%, while United Airlines sank 2.8% and American Airlines fell 4.2% after American rejected a merger overture from United'reversing last week's airline stock gains on merger rumors. On the upside, TopBuild surged 19.4% on news of its $17 billion acquisition by QXO, which would make it North America's second-largest publicly traded building products distributor, though QXO shares dipped 3.1%.

In stock markets abroad, indexes fell in Europe following a better finish in Asia. Germany's DAX lost 1.2%, and Hong Kong's Hang Seng added 0.8% for two of the world's bigger moves.

U.S. Treasury yields were relatively unchanged on Monday after a weekend that saw the Strait of Hormuz reopened and subsequently closed by Iran, with the two-week ceasefire set to expire on Tuesday. The yield on the 10-year U.S. Treasury note ' the key benchmark for U.S. government borrowing ' rose more than 1 basis point to 4.25%.