The US Commodity Futures Trading Commission is investigating a flash crash that occurred on the Coinbase ether trading platform on June 21 where the price plummeted from $317.81 to $0.10 in milliseconds before rebounding, reported Bloomberg.

A single $12.5 million ether trade led other investors to sell their positions and resulted in a cascade of stop-loss orders that only furthered accelerated the flash crash’s momentum. It took approximately 10 seconds before the price of ether bounced back to around $300 per coin.

Coinbase is not registered with the US regulators since it does not trade digital currency derivatives. However, the firm has licenses to operate from several states and the Territory of Puerto Rico.

“As a regulated financial institution, Coinbase complies with regulations and fully cooperates with regulators,” the company said in an emailed statement to Bloomberg. “After the GDAX market event in June 2017, we proactively reached out to a number of regulators, including the CFTC. We also decided to credit all customers who were impacted by this event. We are unaware of a formal investigation.”

According to the news agency, the CFTC’s initial investigation has consisted of a letter inquiring about margin accounts, which the firm began offering in March, as well as other issues.