The U.S. Securities and Exchange Commission has taken its first enforcement action against a cryptocurrency exchange, resolving allegations against the founder of a digital trading platform accused of failing to register his company with the agency.

Zachary Coburn’s EtherDelta marketplace executed more than 3.6 million orders for certain tokens without registering as an exchange, the SEC said in a statement Nov. 8. Without admitting or denying the findings, he agreed to pay a $75,000 fine as well as $313,000 in...