Simpson Thacher & Bartlett has won itself a new trophy client off the back of its highly-rated Tokyo office – advising US drugs giant Merck on its $1.5bn (£924.3m) purchase of 49% of Japan’s Banya Pharmaceutical.

Simpson Thacher’s Japan managing partner David Sneider teamed up with New York partner Alan Klein on the deal, which highlights the attractiveness of Japan’s $50bn (£30.58bn) pharmaceutical market to foreign companies.