Investors placed an approximately $950 million bet on oil prices falling just hours before the U.S. and Iran announced a ceasefire, the latest large wager on the direction of the world's most traded commodity.

The price of oil seesawed in trading in response to U.S. President Donald Trump's imminent threat to obliterate Iranian power plants and bridges.

Earlier, U.S. stocks swung sharply during regular trading as uncertainty about the war with Iran increased after Trump had threatened that a “whole civilization will die tonight."