Korea Financial Supervisory Service cancels large-scale transactions due to system failure at US alternative exchange... ”90,000 accounts, 630 billion won”

The Financial Supervisory Service of Korea announced on the 7th that a service outage at Blue Ocean, which provides trading services for U.S. stocks outside of U.S. market trading hours, had led to losses of 630 billion won (approximately 671 billion yen) in approximately 90,000 investor accounts.
19 Korean securities firms released details about the cancellation of transactions worth 100 billion yen (100 billion yen) during after-hours trading on the U.S. stock market (9:00 a.m. to 5:00 p.m. Korean time).
The company has signed a contract with the US company Blue Ocean to provide intermediary services for "day trading." Blue Ocean said it was unable to respond to the sudden fluctuations in the global stock market on the 5th, which led to a surge in investor orders.
Therefore, the company unilaterally canceled all transactions from 2:45 p.m. Korean time onward. This resulted in the cancellation of orders themselves, and all losses and profits incurred from buying and selling stocks during the day were also cancelled.
After a market closure on the 6th, the company resumed trading on the 7th for only its 29 exchange-traded funds (ETFs).
The Financial Supervisory Service said, “The Blue Ocean trading system, which is mainly for Asian investors,
"However, a sudden increase in order volume exceeded the processing limit, causing the outage," the company said. "It is currently unclear when trading of additional stocks will resume."
South Korean securities firms have been forced to cancel trades with local brokers and brokers.
We checked with Ocean and selected the canceled transactions. We recalculated the margin for each investor, and after restoring the account to former status, we resumed accepting orders. The time it took for this to happen varied from broker to broker.
As of 3 p.m. on that day, the Financial Supervisory Service had received a total of 109 complaints related to this issue.
The Financial Supervisory Service said, "This case was caused by a unilateral cancellation of a transaction due to a system error in the local alternative trading system.
While stating that it is difficult to determine the responsibility of the securities companies, the company also announced that it plans to prioritize coordination between securities companies and investors in order to minimize investor dissatisfaction.
"Investors should also be particularly careful with daytime trading, as all trading volume by Korean investors is carried out through one alternative trading system," he said.
"We will consider measures to enhance the stability of overseas stock investments," he added.