PROFUND was the first commercial investment fund specialized in taking equity positions in microfinance institutions (MFIs) in Latin America and the Caribbean. Its aim was to demonstrate in ten years that investing in microfinance can be profitable and, as it now sells its shareholdings, it has shown that it has achieved this aim. This article describes how PROFUND operates, who have been its investors and MFI investees, and what strategies are now being followed for exiting from investments. Several relevant experiences and lessons learned are summarized. PROFUND has faced a number of challenges: particularly as many of the MFIs have suffered during this period from a poor enabling environment and unfavourable financial climate. Regular technical support for its investees was found to be critical in these circumstances.