US overall has over $7T in foreign sales (that are not exports). S&P 500 has $4.6T or 28% of its revenue overall. With most of the largest market value companies having 50% or more. https://www.visualcapitalist.com/visualizing-the-sp-500s-domestic-and-foreign-revenues/

Very simply, an effective boycott can wipe much more than 28% of stock market. Companies will face much lower US demand as well as a result of unemployment, fewer units of goods able to be purchased, and even service sector inflation. When they say companies will reduce profits to keep US and foreign sales, it means they lose money. US financial sector is actual backbone of US economy, and extremely prone to complete failure/bankruptcies that require bailouts, such as a financial asset crash.

Boycotts are the effective path to ensuring US has a coup over this. Make sure to force your countries to cancel all US weapons purchases, and call out treason for submission/sycophancy response that will come from the same sycophantic traitors that have ruled over you for so long.