US stock futures inched lower as investors digested President Donald Trump's announcement of 25% tariffs on global steel and aluminum imports. Trump imposed 25% tariffs on all steel and aluminum imports on Monday night.

Stock market returns under presidential administrations are more correlation than causation, regardless of what political pundits say.

Stock prices have risen sharply in recent years, but President Trump's new tariffs are causing investor concern. A 25% duty on imports from Canada and Mexico, and a 10% tariff on goods from China, might hurt companies' profitability and competitiveness.