Microsoft Corp is set to acquire a 20% stake in Tokyo-based software developer CIS Corp, according to Japanese business daily Nihon Keizai Shimbun. The purchase – which would be made up of newly-issued shares and some of the personal stake of CIS’s president – would make the US software giant the company’s second-largest shareholder. The move is intended to help Microsoft gain market share in the groupware space with leader Lotus Development Corp, which currently has an alliance with CIS for its Notes software. Redmond apparently wants CIS to make its products compatible with Microsoft Exchange as well.