US stocks mostly weakened Monday after Treasury Secretary Scott Bessent launched “Operation Economic Outcast,” with the S&P 500 down 0.3% and the Nasdaq off 0.6% while the Dow rose 0.2%.
Bessent said the US will expand sanctions on Iran and any country doing business with it, warning those tied to Tehran could be cut off from the US dollar system.
That threat sharpened focus on China—the main buyer of Iranian oil—and added to broader market unease after US-Canada trade talks collapsed and Trump threatened 50% tariffs on Canadian autos, parts and steel from Jan. 1, 2027.
Tech shares also faced pressure ahead of Nvidia earnings on Wednesday, as investors rotated out of semiconductors and memory-chip stocks fell on reports Nvidia plans price increases for some AI servers.