Mizuho Financial Group, a Japanese banking giant, has announced its plans to acquire Greenhill, a boutique investment bank, in a deal valued at USD550m, including debt. The all-cash transaction will see Mizuho pay USD15 per share, representing a 121% premium to Greenhill's stock price prior to the announcement. Mizuho intends to retain Greenhill's leadership, including CEO Scott Bok, who will become chairman of mergers, acquisitions, and restructuring. The move allows Mizuho to expand its presence in US investment banking and fill a gap in its M&A capabilities. The deal comes as other Japanese banks, including Sumitomo Mitsui Financial Group and Mitsubishi UFJ Financial Group, also seek to bolster their investment banking ties in the US. Mizuho plans to complete the acquisition by the end of the year.