[Top Gainers] Oct 22: MS Bio Up 63% on Debut, After Trading 99% Higher

Seoul — As of the Oct 22, 2026 close, KOSPI fell 3.52% to 5,533.77 and KOSDAQ (the tech- and small-cap-heavy market) fell 3.62% to 764.10. Three stocks still rose more than 10%. MS Bio (0013Y0) gained 63.33% on its first trading day with no company filing behind it. SKAI (357880) hit the 30% daily limit a day after three DART (Korea's official disclosure system) filings. Bigwave Robotics (0035S0) rose a fifth straight day on press reports alone.

Key points

• KOSPI -3.52%, KOSDAQ -3.62%. Seoul Shinmun attributed the drop to combined foreign and institutional selling.
• Three stocks rose more than 10%: MS Bio (+63.33%), SKAI (+29.99%), Bigwave Robotics (+12.02%).
• MS Bio traded 10,109 eok won (about 1 trillion won), roughly 2.9 times its closing market cap of 3,466 eok won.
• Foreign and institutional investors were net sellers of SKAI on each of the prior three sessions (Oct 19–21). Same-day investor figures are not out yet.

At a glance

MS Bio (0013Y0): a listing-day rally that narrowed from 99% to 63%

MS Bio debuted on KOSDAQ and closed at 12,740 won. With no prior close, the gain is measured against the reference price at listing. It closed up 63.33%; some outlets reported gains in the 70% range, but this article uses the closing price. Around 1:30 p.m. it stood at 15,560 won, up 99.49%. Headlines in the afternoon spoke of a 'ddoblle' (double the offer price), but the gain narrowed by the close.

The company has filed nothing. Reports from Newsis, Yonhap and Electronic Times describe the listing-day jump, and their headlines give no earnings or contract news. Money flowing into a new listing on a weak day is the most the headlines show; the listing itself is the only confirmed catalyst.

Turnover was about 2.9 times market cap, which shows how crowded listing-day trading was. To judge whether this lasts, check the lock-up expiry date for institutional holders and the free float first. Also watch whether turnover holds the next day and whether the stock stays above its 12,740 won first-day close.

SKAI (357880): limit-up the morning after three filings

SKAI closed at the 1,851 won limit. It rose 25.6% over two sessions and 29.2% over five. According to DART, three major-matter reports were filed on Oct 21: a convertible bond issue, a capital-recognized debt security issue, and an acquisition of shares in another company. Data Investment headlines put the perpetual convertible bond at 22.8 billion won and the share purchase of Sky Intelligence at 25.35 billion won. The purchase equals about 25% of the 1,026 eok won closing market cap.

The filings alone do not prove why the stock jumped. Etoday headlined 'AI expectations lift SKAI and Agent AI to the limit', and on Oct 21 there was a report on SKAI joining a physical-AI global white paper. The company has not said which mattered more. Bond issuance is financing and a share purchase is a business decision, so neither is the kind of earnings result that can be checked in the numbers. Foreign and institutional investors were net sellers on each of the prior three sessions; individuals bought.

To judge whether this lasts, watch whether the company or later filings spell out the business of the acquired firm and how the funds will be used. Also check whether day-two turnover stays near today's 287 eok won.

Bigwave Robotics (0035S0): fifth straight gain on a platform report, with no company filing

Bigwave Robotics rose 12.02% to 23,300 won, its fifth straight gain and 68.1% over five sessions. The reported reason is the launch of a physical-AI development platform. Chosunbiz wrote 'up 14% on news of a physical-AI development platform launch', and Financial Post reported a platform event with Nvidia and Rainbow Robotics. Recent DART filings cover only an extraordinary shareholder meeting, a record date and an executive holding report, so nothing filed confirms the platform or a contract.

Around 1:30 p.m. it was up 20.19% at 25,000 won and closed at 12.02%. Since our Oct 20 article, which cited reports as the basis, it has risen another 26.6%. It still sits about 40% below its peak close of 38,850 won (Sept 30), on its 16th trading day since listing. Foreign and institutional investors sold on Oct 20 and 21 while individuals bought.

Watch whether turnover (1,307 eok won today) holds up and whether the company confirms the platform launch in its own filing or release.

What happened to stocks we covered before

Both stocks backed by filings rose on a day KOSDAQ fell 3.6%. Of the five that rested on reports alone, only Bigwave Robotics rose sharply and the other four fell. Ellis, with no identified reason, gained 16.3%. The sample is too small to generalize.