A venture capital fund manager who promised the public pre-IPO shares in taxi company Uber Technologies and Twitter instead took retail investors for a ride in a Ponzi scheme, the Securities and Exchange Commission said Friday.

The SEC froze the assets Gregory W. Gray Jr. and his firms Archipel Capital LLC and BIM Management LP in a successful plea to the U.S. District Court for the Southern District of New York.

Gray allegedly took $5.3 million from investors two years ago, promising them Twitter stock before the social media company went public.

Instead, said the SEC, he stole the money and when pressured by the investors who wanted to cash out, Gray paid them from $5 million he received from a man who thought he was investing in Uber.

The SEC said its investigation against Gray is continuing.

When told about the ruse, Madoff whistleblower Harry Markopolos told Financial Advisor magazine, he had never heard of a Ponzi fraudster taking this tact and was surprised the investors were taken in. “That investors actually believed retail investors can buy pre-IPO shares at a substantial discount shows we have a long, long way to go with investor education,” Markopolos said.