Tariffs and an imminent trade war were shots across the market’s bow Monday morning, but irrational exuberance is what made the market so vulnerable in the first place. I say that because the weekend announcement of the tariffs couldn’t reallybe the cause of the plunge at Monday’s opening.

Tesla was particularly battered as it joined Apple (-3%) and Nvidia (-3%), as American multinational companies with the highest proportion of sales in China.

The stock market fell on Monday after President Donald Trump slapped tariffs on Canada, Mexico and China, eliciting threats of retaliation and setting the stage for a trade war. Traders demonstrated their jitters with a selloff of U.