Even the IRS makes mistakes.

In a rare apology, the Internal Revenue Service issued a statement apologizing for the “thousands” of tax documents leaked to the public between 2018 and 2020, including the records of billionaire and Citadel CEO Ken Griffin, who was directly named in the statement.

The apology is part of a settlement Griffin made with the IRS following a lawsuit he filed in December 2022 over the “unlawful disclosure” of his tax information that was leaked to the public by a contractor.

The IRS said the contractor, Charles Littlejohn, shared the information with the press and “violated” the terms of his employment. The agency added that Littlejohn “betrayed the trust” of Americans, including billionaire Elon Musk.

Related: Read Citadel CEO Ken Griffin’s Internal Memo on Top Hedge Fund

“The IRS takes its responsibilities seriously and acknowledges that it failed to prevent Mr. Littlejohn’s criminal conduct and unlawful disclosure of Mr. Griffin’s confidential data,” the IRS said in a statement. “Accordingly, the IRS assures Mr. Griffin and the other victims of Mr. Littlejohn’s actions that it has made substantial investments in its data security to strengthen its safeguarding of taxpayer information.”

^{Ken Griffin, founder and CEO of the hedge fund Citadel LLC, speaks at the Milken Institute’s Global Conference (Apu Gomes/Getty Images)}

Littlejohn was sentenced in January to a five-year prison sentence.

The IRS added that it was making “substantial investments in its data security to strengthen its safeguarding of taxpayer information.”

Griffin’s net worth is an estimated $42 million and hit a record in 2022 when Citadel made the most money on record of any hedge fund in a given year. In 2023, Citadel’s overall earnings reached $74 billion.

Related: The Door Is Slamming Shut on a $50 Billion Tax Loophole Used By the Superrich

“I am grateful to my team for securing an outcome that will better protect American taxpayers and that will ultimately benefit all Americans,” Griffin told CBS MoneyWatch in a statement, regarding the tax leak.