Billionaire investor and fund manager Ron Baron said Wednesday he owned more than $1 billion worth of shares in Elon Musk's rocket company SpaceX, in an interview to CNBC.

"We're one of the largest investors in SpaceX," said Baron, who is a close aide to Musk and has a long-time position in his electric car company Tesla. He has also reportedly invested $100 million as part of Musk's take-private deal for X, formerly Twitter.

His firm Baron Funds has been purchasing privately owned SpaceX stock since 2017, according to the investor's quarterly report from March.

Reuters in November reported that SpaceX was in talks to raise external funding, mostly comprised of secondary shares sale, at a valuation of up to $150 billion.

SpaceX, which counts Alphabet and Fidelity Investments among its investors, had raised about $1.68 billion through equity financing in June last year.

On Tesla, Baron said in the interview the electric-vehicle maker could be four-five times bigger in the next seven years. In June, he had said the Tesla stock could hit $500 by 2025.