Trump Media’s Stock Plunges After Debate

Wall Street gave a thumbs down to former President Donald J. Trump’s debate performance on Tuesday night, judging by the trading in shares of his social media company.

Shares of Trump Media & Technology Group, the parent company of Truth Social, were poised to open more than 10 percent lower on Wednesday, the morning after the debate between Mr. Trump and Vice President Kamala Harris.

Since Trump Media’s debut on Wall Street in March, the company’s stock has traded as something as a proxy for Mr. Trump’s prospects in the November presidential election. Commentators, including members of Mr. Trump’s Republican Party, concluded that Ms. Harris put Mr. Trump on the defensive and provoked him into veering off message.

If the premarket trading were to hold after the official open of trading in New York, shares of Trump Media would fall to their lowest level since the money-losing company went public in March, after its merger with a cash-rich shell company called Digital World Acquisition Corp.

On the day of the debate, shares of Trump Media had rallied somewhat, although the stock is still down more than 70 percent from its post-merger closing high.

The sell-off in shares of Trump Media has come at an inauspicious time for Mr. Trump, who owns about 57 percent of the company’s stock. In just over a week, on Sept. 19, a provision that prohibits him and other large shareholders from selling stock is set to expire.

Mr. Trump’s shares were worth about $2 billion at the market close on Tuesday. Trump Media’s falling share price has reduced the paper value of his stake in recent months by about $4 billion. Premarket trading on Wednesday implies that the value of his stake would fall by more than $200 million.

Mr. Trump now faces a