Billionaire Ron Baron has sold 1.8 million Tesla shares for customers in the past six months, despite believing the stock will climb to $ 2,000 over the next 10 years.

Baron, a longtime Tesla shareholder, said Thursday morning on CNBC’s “Squawk Box” that his eponymous company sold the shares because they made up too large a percentage of some portfolios.

“It was painful to sell every single share,” he said, adding that he had not sold any of his 1.1 million-plus shares in the electric car maker. He said “risk mitigation” is appropriate for his customers to sell their Tesla stock.

Baron Capital held just over 6.1 million Tesla shares as of February 28. They were purchased at an average price of $ 42.34 per share.

Tesla’s shares rose 338% over the past year to $ 653.20 per share. The market capitalization is around $ 619.2 billion.

Baron said he plans to hold on to his shares for “at least 10 years” and told Tesla CEO Elon Musk that he “would be the last.”

“We’re looking for a lot more,” said Baron. “I think our goal in 10 years is $ 2,000 per share.”

In June, Baron told CNBC that he believes Tesla stock has “ten times more to do”. Shares have since shot higher. Then in October, Baron said he believed Tesla would eventually become a $ 2 trillion company.

Baron has diversified its investments in electric and autonomous vehicles outside of Tesla. Most notably, he said his firm is an investor in privately owned EV start-up Rivian – an up and coming rival of Tesla – as well as in Cruise, an autonomous vehicle company majority-owned by General Motors. He said his company invested $ 10 million in Cruise.