The Korea Exchange noted on the 18th that the temporary suspension of KOSPI transactions during the day was due to issues with the middle price quoting of Tongyang Steel Pipe.
The exchange explained that "a conflict arose between the existing self-transaction prevention conditions (SMP) trading logic of Tongyang Steel Pipe and the introduction of the middle price quoting, resulting in an error during the trading day."
SMP (Self Match Prevention) is a mechanism that prevents mutual execution when the transaction ID is the same. When calculating the transaction quantity of the SMP quote for Tongyang Steel Pipe, the quantity for the middle price quote was omitted, causing a delay in the transaction execution.
According to the exchange, the trading execution system for KOSPI market items halted from 11:37:07 a.m. on that day. After 7 minutes, from 11:44:16 a.m., the system was restored, and the quotes were received normally. However, transactions for Tongyang Steel Pipe were suspended from 12:05 p.m. to 3 p.m. on that day.
The exchange explained that there was an error that could occur when the quote price unit is 1 won (for items priced under 2,000 won) and the quote spread is 1 tick (1 won, the minimum price fluctuation unit), leading to the truncation of the middle price quoting. Currently, there are 129 such items listed in the KOSPI market and 428 in the KOSDAQ.
The exchange held a company-wide inspection meeting to check for other issues in the system execution logic after the market closed and confirmed that there were no additional problems.
As of the 31st, the trading items on the alternative exchange, Next Trade, are set to expand to 800 items, and the exchange plans to conduct joint inspections. An exchange official said, "To prevent similar cases, we plan to conduct joint inspections with Next Trade every weekend until the end of April."