MTN Group’s biggest shareholder is pushing for changes at Africa’s largest mobile-phone company to avoid the regulatory, legal and political disputes that have cut its share price by more than half over the past four years. The Public Investment Corporation built a 26% stake in Johannesburg-based MTN by late November and used that to call for the replacement of chairperson Phuthuma Nhleko, people familiar with the matter said. Africa’s biggest fund manager, which is South African State-owned, also sent a letter to MTN demanding a board reorganisation, said one of the people. That resulted in the appointment of more politically connected directors.