Stocks have plunged in amid fears that tariffs will weigh on economic growth. Yet, there may be a more under-the-radar reason behind the sell-off.

The U.S. stiock market has dropped considerably over the last week amid concerns over the impacts of President Donald Trump's proposed tariffs.

The S&P 500 is set to have its worst day of the year, decreasing by more than three percent by Monday afternoon. This comes just one day after Trump refused to rule out the possibility that his trade war could lead to a recession later this year.