(Bloomberg) -- Interactive Brokers Group Inc. will pay a $1.75 million fine after the U.S.’s futures regulator alleged it failed to adequately prepare its electronic trading system before oil’s historic plunge in April 2020.  

When the price of oil dropped below zero on April 20, 2020, the negative price wasn’t displayed for Interactive Brokers customers nor could they place limit orders to buy or sell, according to a Tuesday statement from the Commodity Futures Trading Commission. The flaw impacted hundreds of customer accounts that held oil futures, triggering losses that exceeded $80 million. 

“This enforcement action demonstrates that the CFTC will hold registrants responsible for their handling of customer accounts and ensuring the integrity of trades on their trading platforms and electronic systems, including during instances of market volatility,” said Vincent McGonagle, the CFTC acting enforcement director. 

Interactive Brokers agreed to the penalty without admitting or denying the regulator’s findings. The firm said it has already paid $102 million in restitution to harmed customers, beyond the $82.7 million required by the CFTC. The regulator said it reduced the brokerage’s fine as a result of its substantial cooperation during the investigation. 

“We are pleased to resolve this matter and pleased that the CFTC recognized our proactive compensation of our affected customers,” Interactive Brokers said in a statement. 

The price of crude plunged in the final minutes of trading on April 20, 2020, a slide that traders attributed to storage issues and the global economic slowdown that was prompted by the coronavirus pandemic. 

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