WASHINGTON, D.C. — A surge in oil and S&P 500 futures trading occurred at 6:49 a.m. Eastern on Monday, March 23, shortly before President Donald Trump announced he had instructed the Pentagon to postpone strikes on Iran for five days. Roughly six thousand oil-trading contracts worth more than half a billion dollars changed hands during the surge.

Trump announced on social media shortly after 7 a.m. that the United States and Tehran were engaged in talks about a complete and total resolution of hostilities in the Middle East. Following the announcement, the price of crude oil plunged by more than 10 percent while stock futures jumped by about 2.5 percent.

The volume of trading just before the announcement was roughly nine times the average volume at the same time during the previous five days. A surge of activity in contracts tied to the S&P 500 stock index occurred immediately after the oil-trading surge. Other traders deduced from price movements that someone was selling oil futures and buying stock futures.

There is no public evidence identifying who placed the trades that preceded the postponement announcement. Some of the trades were so large that the trader would have needed tens of millions of dollars in margin reserves.

"The timing and the fact that the two trades were placed at the same time, it kind of smells like something was off," said Mike Khouw, a portfolio manager and veteran futures trader. "You are not dealing with a rube. You are not dealing with someone whose other occupation is working at Starbucks."

The White House pointed out that federal employees are barred from profiting from nonpublic information and stated: "Any implication that Administration officials are engaged in such activity without evidence is baseless and irresponsible reporting."

The Commodity Futures Trading Commission is the agency with primary responsibility for enforcing the laws in the futures markets. The CFTC did not respond to a question about whether it had launched an investigation.

"The thing that should be happening is that the CFTC should be investigating these trades," said Ben Schiffrin, a former SEC attorney and public-interest group representative. "They have the authority to subpoena trading records and find the identity of the people who placed the trades. Insider-trading investigations happen all the time, and that's how they work."

"The CFTC seems to be more focused on promoting crypto, prediction markets, and A.I. than its core function: investigating and preventing manipulation in the futures markets," Schiffrin said.