International private equity has become the fastest growing source of investment in sub-Saharan Africa but better risk management tools and a way to develop whole sectors was needed to make sure benefits are spread more widely, a study found. In recent years, investors tired of low returns in developed markets have increasingly looked to cash in on the rapid growth and emerging middle-class consumers in Africa, home to many of the fastest expanding economies in the world. Investments from international private equity has grown five-fold since 2008 across sub-Saharan Africa and now amounts to around $12 billion, or 20 percent, annually of cross-border investments, a working paper released on Tuesday by the Overseas Development Institute (ODI) said.