Washington's new Iran sanctions and Canada tariff threat rattle markets

Washington escalated economic pressure on two fronts Monday, unveiling tough new sanctions against Iran and threatening to double auto tariffs on Canada to 50%. Markets braced for a busy week ahead. Treasury Secretary Scott Bessent announced an "economic D-Day" campaign to isolate Iran, threatening to remove any entity facilitating Iranian money laundering from the U.S. dollar system. President Donald Trump vowed to double tariffs on Canadian autos and steel to 50% effective January 2027, with both sides blaming each other for stalled trade negotiations. Wall Street opened lower, with the S&P 500 falling 0.28% and Nasdaq dropping 0.76% on chip stock weakness. Investors await Nvidia's earnings Wednesday, July inflation data, and Fed Chairman Kevin Warsh's Jackson Hole speech Friday. Treasury may use its near-$1 trillion account to fund expanded bond buybacks.