This is true - all the global multinationals that essentially make the US stock market earn a good portion of their revenue in foreign currency, so their revenu

This is true - all the global multinationals that essentially make the US stock market earn a good portion of their revenue in foreign currency, so their revenue and profits will increase. In addition, they are all cheaper when priced in USD, so their stock will go up regardless. This is just counting short term effect of currency devaluation. Long term there are also effects around trade balance and jobs.