Elliott Investment Management has built a significant stake in real estate developer Sumitomo Realty & Development, according to people familiar with the matter.

The activist investor has engaged with Tokyo-based Sumitomo Realty on measures to improve shareholder value, the people said, asking not to be identified because the matter is private.

Elliott has a number of investments in Japan that have focused on boosting returns through share buybacks, selling off older real estate holdings and unwinding equity stakes in other companies.