By Dave Michaels, Justin Scheck and Shane Shifflett

Updated Nov. 15, 2018 5:08 p.m. ET

Securities regulators are investigating a company's $50 million cryptocurrency sale, an executive with the firm said, and people familiar with the probe said it includes looking at whether a prominent bitcoin entrepreneur broke the law by getting involved with the company's fundraising.

The entrepreneur, Erik Voorhees, is chief executive of ShapeShift AG, a digital-asset exchange that suspected criminals have used to launder millions of dollars in allegedly ill-gotten gains, The Wall Street Journal reported earlier this year. Law-enforcement officials in the U.S. and abroad have looked at ShapeShift's role in processing assets in several criminal cases, people involved in those investigations told the Journal.

Now, the Securities and Exchange Commission is probing another company that has been affiliated with Mr. Voorhees, Salt Lending Holdings Inc. The company, which loans money to people using their cryptocurrency as collateral, received a subpoena from the SEC in February seeking records related to a $50 million digital-token sale it held last year, the people familiar with the matter said.

Among other issues, regulators are looking at whether Salt's token sale should have been registered with the SEC as a securities offering; how Salt insiders received tokens; how token proceeds were used; and whether raising money while Mr. Voorhees served on Salt's board violated a 2014 SEC settlement that banned Mr. Voorhees from such fundraising, according to the people familiar with the probe. An SEC spokesman declined to comment.

The Salt probe comes amid a wave of SEC investigations into cryptocurrency companies. Regulators say many of the deals violate investor-protection laws because they don't provide buyers with required financial information and risk disclosures.

Mr. Voorhees is a critic of regulation who referred to government-backed currencies as "scams" in a recent interview posted on the YouTube channel NBTV. In an interview with the Journal last summer he said "this whole narrative that the government is out to protect people is total bullshit."

He has said exchanges such as ShapeShift, don't have to follow federal laws requiring financial companies to know who their clients are and to file suspicious-activity reports with the government when potential money laundering is discovered. The U.S. Treasury Department says such exchanges must follow anti-money laundering rules, though the law in the area remains largely untested.