Monolith Soft was originally created by founders Hirohide Sugiura, Tetsuya Takahashi and Yasuyuki Honne with investment from Namco (now Bandai Namco) to work on Xenosaga, a Namco-owned spiritual successor to Square’s Xenogears. In 2007, Nintendo bought out 80% of Monolith Soft’s shares from Namco, and then went on to further increase its stake to 96% in 2011.
Up until recently, Monolith Soft’s founders have maintained a symbolic 4% stake in the company, but it seems Nintendo has acquired the remaining shares. We don’t know when exactly this happened, but Sugiura, Takahashi and Honne still owned 4% percent of Monolith Soft at least until March this year, when their
company brochure for 2024 (relevant excerpt below) was published.