A system glitch at a cryptocurrency exchange site run by an Osaka-based firm enabled users to obtain digital money for free, with one apparently “purchasing” Bitcoin valued at 2,200 trillion yen ($20 trillion) and then attempting to cash in on it.

Tech Bureau Corp., a registered cryptocurrency exchange operator, is now subject to a Financial Services Agency investigation into the safety of the system and other business practices.

The company announced Feb. 20 that the incident on its Zaif exchange website occurred four days earlier, when seven users obtained quantities of cryptocurrencies. Tech Bureau later invalidated the transactions and corrected the users’ balances.

The glitch, which lasted for 18 minutes from 5:40 p.m. to 5:58 p.m. on Feb. 16, affected Zaif’s price calculation system, enabling customers to buy cryptocurrencies for nothing.

As at least one “buyer” attempted to resell their Bitcoin, an abnormally high quantity of the cryptocurrency appeared for sale on Zaif, and word soon spread on the Internet that around 2,200-trillion-yen worth of Bitcoin was on sale there.

The problem was rectified by 7:34 p.m. the same day.

A Tech Bureau official apologized to customers for the trouble and pledged to take measures to prevent further glitches.