NEW YORK (AFP) ― U.S. antitrust officials have fined Warren Buffett’s Berkshire Hathaway $896,000 for failing to notify regulators ahead of a large securities acquisition in December 2013.

Berkshire agreed to pay the civil penalty to resolve the case over the December 2013 purchase, the Justice Department said Wednesday. The settlement must be approved by a U.S. court.

“We made a mistake when we overlooked the filing requirement,” Buffett said in a statement.

The company ran afoul of U.S. antitrust requirements when it failed to file papers announcing a purchase of securities in building products company USG that ended up taking its overall stake in USG to more than $950 million.

Federal law requires Berkshire to provide advanced notification to regulators of purchases that lift its holding in another entity to more than $283.6 million, the Justice Department said.

The rule is intended to give antitrust regulators an opportunity to determine whether to block deals that may flout antitrust laws.

Berkshire, a holding company with stakes across many sectors, previously violated the notification requirement with a June 2013 purchase of shares in life insurer Symetra Financial that took its holdings to more than $310 million.

Buffett said Berkshire’s USG securities stake grew when USG redeemed convertible notes that Berkshire had originally purchased in 2008.

Berkshire “was effectively forced to convert the notes when they were called for redemption by USG in December 2013,” Buffett said.

“This event triggered a filing requirement for Berkshire and we were late in realizing that fact.”