• The stock price of Trump Media dropped a day after majority shareholder Donald Trump benefited from President Joe Biden stumbling through their first presidential debate.
• Trump is the majority shareholder of Trump Media, which trades under the DJT ticker.
• Trump Media is the owner of the Truth Social app often used by the Republican candidate.

The stock price of Trump Media closed down nearly 11% Friday afternoon, a day after majority shareholder Donald Trump saw President Joe Biden stumble through their first presidential debate.

Trump Media, which trades under the DJT ticker, in premarket trading Friday morning had been up by more than 11% in premarket trading. But the company ended the day at $32.75 per share, a decline of 10.84%

The Truth Social app owner's share volume was heavy, with more than 24 million shares changing hands.

Trump, the former president who is the presumptive Republican nominee, owns almost 65% of Trump Media shares. The company's market capitalization stood at $5.8 billion Friday despite having meager revenue.

Political observers and Democratic donors said Biden, 81, gave a dismal performance on Thursday night in his debate against Trump at CNN's studios in Atlanta. Biden's speech was garbled at times. He also lost his train of thought, and his face looked blank with his mouth agape at times as Trump spoke.

One major Democratic fundraiser told CNBC that Biden's performance was a "disaster."

"This is terrible. Worse than I thought was possible. Everyone I'm speaking with thinks Biden should drop out," that donor said.