Shares of Nissan (NSANY, 7201.T) tumbled on concerns about its deal with Honda (HMC, 7267.T), which isn't expected to close until 2026. One of the concerns is the starting ratio. According to Nikkei analysis,

Key Takeaways U.S.-listed shares of Honda jumped Monday morning after the Japanese automaker and Nissan announced plans to merge.The sides signed a memorandum of understanding Monday, with plans to finalize details in June 2025 and merge in August 2026.

The proposed deal aims to unify operations under a joint holding company, led by Honda, while maintaining the distinct identities of each brand, according to Honda's president, Toshihiro Mibe. If finalized, the merger would position the combined entity to better compete with market leaders Toyota and Volkswagen.