Exclusive
Dunamu Finalizes Victory in Patent Dispute Over Unlisted Stock Trading with Seoul Exchange

[비즈한국] 'Seoul Exchange Unlisted' (operated by Seoul Exchange), a platform for unlisted stock trading, has ultimately lost its patent dispute with Dunamu, the operator of 'Stock Plus Unlisted'. Seoul Exchange had been engaged in a patent dispute over unlisted stock trading technology with Dunamu, the former parent company of Stock Plus Unlisted, since 2024. Recently, the Supreme Court dismissed Seoul Exchange's appeal, finalizing the judgment that upheld the invalidation of the patent claimed by Dunamu.

The patent infringement dispute between Seoul Exchange and Stock Plus Unlisted (formerly under Dunamu) concerning one-on-one unlisted stock trading has concluded after about two years.

On March 12, the Supreme Court dismissed the appeal filed by Seoul Exchange against Dunamu in the lawsuit to revoke the patent invalidation ruling, citing a lack of grounds for review, thereby confirming the original ruling in favor of Dunamu.

The patent dispute between the two companies dates back to 2024, when Dunamu held Stock Plus Unlisted as a subsidiary. The conflict began in March 2024 when Stock Plus Unlisted launched its 'Instant Partial Execution' service. This feature allows users to execute trades for even a portion of the quantity when conditions, such as price, are met upon registering a buy or sell order. The process requires either the buyer or seller to accept the order just before the trade.

In May 2024, Seoul Exchange sent a content-certified mail to Dunamu, claiming that Stock Plus Unlisted had copied the 'Instant Partial Execution' feature from Seoul Exchange Unlisted. Seoul Exchange’s 'Instant Partial Execution' is a feature that allows immediate trading of even partial quantities without further negotiation between buyer and seller if their desired conditions are met. Seoul Exchange had also filed for a patent upon launching this service.

Dunamu responded to Seoul Exchange's challenge by filing a patent invalidation trial. Dunamu argued that Seoul Exchange’s service was easily derived by combining existing technologies, thus lacking innovation. On October 31, 2024, the Intellectual Property Trial and Appeal Board issued a decision upholding Dunamu's claim. Patent-related legal disputes follow a structure where the Intellectual Property Trial and Appeal Board serves as the first instance, the Patent Court as the second, and the Supreme Court as the final instance.

Seoul Exchange filed a lawsuit with the Patent Court to cancel the Intellectual Property Trial and Appeal Board's decision. Seoul Exchange argued that its technology was one that "minimizes negotiation procedures between buyer and seller in one-on-one over-the-counter (OTC) stock trading and prevents fake listings, which have occurred frequently in OTC trading," adding that it "improved upon the drawback of not being able to execute partial trades without separate negotiations and was unpredictable from prior inventions."

However, in October 2025, the Patent Court dismissed Seoul Exchange's claim. It determined, as Dunamu argued, that the patented technology of Seoul Exchange was easily derived by combining prior inventions, and therefore lacked inventive step. Seoul Exchange appealed the Patent Court's ruling, but the Supreme Court dismissed it on the 12th, finalizing the lower court's decision.

Currently, Stock Plus Unlisted is owned by Naver035420 Financial (Naver Pay). This follows Dunamu’s sale of a 71.73% stake in its former 100% subsidiary, Stock Plus Unlisted, to Naver Pay and Naver in September 2025. Currently, the largest shareholder of Stock Plus Unlisted is Naver Pay with 65.96%, while Dunamu's stake has decreased to 28.27%.

Recently, on April 27, Stock Plus Unlisted announced a rebranding plan to change its corporate name to 'Naver Pay Unlisted' and its service name to 'Npay Unlisted'. Naver Pay operates the financial investment content platform 'Npay Securities', and it is expected that the unlisted stock service will be provided on that platform after the rebranding. Stock Plus Unlisted explained, "The change in service name is an extension of the changes following the incorporation as a Naver Pay subsidiary, intended to allow more individual investors to participate in the unlisted stock market."

Although Dunamu has concluded the patent dispute with Seoul Exchange, the controversy over the monopoly on stock trading remains. In February, the Korea Fair Trade Commission (KFTC) conducted an on-site investigation regarding allegations of unfair trading practices by Dunamu. Previously, it was reported that Seoul Exchange had filed a complaint with the KFTC against Dunamu, claiming that Dunamu prevented its own shares from being traded on Seoul Exchange Unlisted. Dunamu shares, which are unlisted, can be traded on Stock Plus Unlisted. Dunamu did not comment on the KFTC investigation.