Rainier Acquisition Corporation

We are a blank check company incorporated on February 2, 2023 as a Cayman Islands exempted company. We are incorporated for the purpose of effecting a merger, amalgamation, share exchange, asset acquisition, share purchase, reorganization or similar business combination with one or more businesses, which we refer to throughout this prospectus as our initial business combination. We seek to partner with companies that can benefit from our scientific, investing, operating, capital markets, governance, and public-company leadership experience, and we seek to support long-term value creation through our experience, relationships, and access to capital. To date, our efforts have been limited to organizational activities as well as activities related to this offering. We have not selected any specific business combination target and we have not, nor has anyone on our behalf, initiated any substantive discussions, directly or indirectly, with any business combination target. We have generated no operating revenues to date, and we do not expect that we will generate operating revenues until we consummate our initial business combination.

Current securities

1. Other EventsSep 11, 2026
2. 3 filingSep 8, 2026
3. Unregistered Sales of Equity Securities · Other EventsSep 3, 2026
4. Entry into a Material Definitive Agreement · Unregistered Sales of Equity Securities · Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements · Amendments to Articles of Incorporation or Bylaws; Change in Fiscal Year · Other EventsAug 28, 2026
5. 424B4 filingAug 27, 2026