Investing.com -- Investors placed a bet worth about $760 million on a falling oil price around 20 minutes before Iran’s foreign minister announced on Friday that the Strait of Hormuz was open, another sizeable wager on the world’s most traded commodity ahead of major announcements in the course of the Middle East war.

Between 1224 GMT and 1225 GMT, investors sold a combined 7,990 lots of Brent crude futures LCOc1, Reuters reported, citing LSEG data. At the time, these trades were worth about $760 million.

The move led to U.S. crude oil plunged 12% to around $83 per barrel, while international Brent crude also slid more than 10% to around $89 per barrel.

"In line with the ceasefire in Lebanon, the passage for all commercial vessels through Strait of Hormuz is declared completely open for the remaining period of the ceasefire," Iran’s foreign minister Abbas Araghchi said on X.

These large, strategic trades have fueled speculation among analysts about the potential influence of war-related policy shifts on commodity markets, raising concern among U.S. lawmakers and legal experts about possible trading advantages in volatile oil derivatives markets.

Reuters earlier reported that on April 7, those bets, worth around $950 million, were placed just hours before the U.S. and Iran announced a two-week ceasefire, a move that can sway oil prices. On March 23, investors sold $500 million in oil futures 15 minutes before U.S. President Donald Trump announced he would delay attacks on Iran’s energy infrastructure, prompting a 15% drop in crude prices.

Iran’s move followed President Trump’s announcement of a 10-day ceasefire between Israel and Lebanon. Israel’s continued attacks on Hezbollah had complicated negotiations between Iran and the U.S.

Hopes for a lasting end to hostilities improved sentiment this week, pushing the S&P 500 and Nasdaq to record highs—a rebound for Wall Street after the conflict began in March.