SK Group Chairman Chey Tae-won’s high-profile divorce from his estranged wife Roh Soh-young took an unexpected twist after the Seoul high court made a rare rectification of a mistake in its ruling that ordered the chaebol chief to pay $1 billion in property division to the wife.

On Monday, the appellate court corrected numerical errors in its written judgment for the divorce settlement of Chey and Roh, but upheld its overall ruling involving the record-high divorce settlement.

Earlier in the day, Chey’s attorney argued that the court made a mistake in evaluating the value of the SK stocks Chey owns. This led to the court's miscalculation of how much their value had grown since Chey took ownership of them, and the chairman's level of contributions to the company, according to Lee Dong-keun, Chey's attorney from the Yoon & Yang law firm.

The court initially calculated the value of one Daehan Telecom share at 8 won in November 1994 when Chey purchased the stocks with the money he received from his father Chey Jong-hyun. Daehan Telecom, renamed SK C&C in 1998, is the origin of SK Inc., the group’s holding unit.

The court made a mistake by valuing the company stock at 100 won per share, when it should have been 1,000 won, in May 1998 -- when the former chairman passed away. From then to November 2009 when SK C&C went public, the court valued the company at 35,650 won per share.

So the court initially concluded that Chey Tae-won's contribution led the company to grow 335 times bigger, while his late father contributed to the company's growth by 12.5 times. But the actual figures should be 125 times for the father’s contributions and 35.5 times for the son’s contributions.

Based on the correct calculations, Chey’s legal team argues that the court should revisit the logic flow in designating what should be seen as joint property of Chey and Roh, hinting at an appeal to the Supreme Court.

Views are mixed among legal experts.

“It is quite rare that the court makes such a mistake and corrects the error,” said Lee Hyung-gon, a judge-turned-lawyer. However, Lee remained cautious about whether the correction would affect the ruling.

“It remains to be seen whether the Supreme Court finds the numerical mistake as critical or not.”

He added that the more critical part could be Roh’s claim of her father giving slush funds to Chey, which the SK chief flatly denies.

In 2022, the top court dismissed 93.6 percent of appeals in family litigation cases.

The direction of the case is expected to be decided four months after the appeal is filed, the period during which the top court has to decide whether to dismiss or hear the case.

'Fat-finger’ failures

Industry officials say the mistake could be a “fat-finger” error, which refers to problems caused by inputting wrong data, often in financial markets. The errors sometimes snowball into financial losses or trigger significant market impact.

For instance, a trader at Citigroup’s subsidiary processed a $444 billion order meant to amount to just $58 million in 2022. The blunder led the US banking giant to face a $79 million fine from UK regulators for lacking control over its trading operations in May.##

Sometimes, numerical blunders escalate into the collapse of a securities firm.

Korean brokerage house HanMag Securities declared bankruptcy in 2013 after a mistake when inputting settings for automatic index options transactions caused it to suffer an unexpected loss of 46 billion won

In 2005, Japan's Mizuho Securities mistakenly offered to sell 610,000 shares of telecom outsourcing firm J-Com for 1 yen each, instead of one share for 610,000 yen, which cost the firm losses of 40 billion yen ($253 million). The blunder led to a massive fluctuation in J-Com’s stock value. Investors ditched securities equities, which later evolved into a broader market sell-off, bringing down the overall stock market prices.