Hisamitsu Pharmaceutical surged the most in more than 47 years after the Japanese maker of pain-relief patches announced it would go private in a management buyout valued at about ?457 billion ($2.9 billion).

The shares jumped by the daily limit, closing 19% higher, the biggest gain since August 1978. The stock rose 16% a day earlier after Bloomberg reported of a potential deal involving an entity controlled by Chief Executive Officer Kazuhide Nakatomi, a member of Hisamitsu¡¯s founding family.

The proposed offer of ?6,082 per share represents a roughly 35% premium to Hisamitsu¡¯s unaffected closing price on Monday. The company confirmed the plan, saying the tender offer will run from Jan. 7 to Feb. 19. The acquirer plans to borrow funds from Sumitomo Mitsui Banking and Mitsubishi UFJ Financial Group for the deal, according to the statement.

Known for its Salonpas pain-relief patches, Hisamitsu joins a growing list of Japanese companies exiting the public market to shield themselves from regulatory and investor pressure to lift valuations and implement more oversight. As a result, the number of firms traded on the Tokyo Stock Exchange is falling for the first time in more than a decade as buyouts and restructuring-related delisting reached a record last year.

At the same time, the Japanese government has been promoting cheaper generic medicines and pushing drugmakers to cut prices as its population ages. In October, Hisamitsu said operating profit fell 9.7% to ?8.1 billion for the six months ended August 2025, hurt by the measures, and also weaker domestic sales of Salonpas.

To promote growth, Hisamitsu is stepping up overseas expansion as it faces intensifying competition at home. In the coming years, Hisamitsu plans to invest more than ?50 billion to expand Salonpas supply and more than ?150 billion in research and strategic investments, the drugmaker said in October.

The company¡¯s strategy is centered around maximizing the value of prescription drugs, developing new products using microneedle technology, which enables faster, more efficient and user-friendly drug delivery, while restructuring the over-the-counter drug business, strengthening global expansion, and expanding e-commerce sales, Hisamitsu said in the statement.

¡°Going private will enable us to make management decisions from a long-term perspective and actively invest in research and development,¡± Hisamitsu said.

Domestic rival Taisho Pharmaceutical Holdings¡¯ management privatized the company in 2024, citing the need to focus on mid- to long-term strategies rather than short-term profits and shareholder returns.

Hisamitsu, which traces its origins to 1847 in Saga prefecture in southwestern Japan, develops and sells prescription and drugstore products. Salonpas became the first-ever topical pain-relief patch approved by the U.S. Food and Drug Administration in 2008.