Résumé : Microfinance, which pledges to provide financial services to people without access to banking, is chiefly run by non-governmental organizations (NGOs). Little is known about the extent to which the transformation of these NGOs into shareholder-owned and, most often, regulated firms affects the way microfinance institutions (MFIs) conduct their business. By applying the event study methodology to 66 MFIs that have transformed, we quantify the effect that transformation has on the MFIs’ business models. Our results suggest that portfolio yield is driven down by 3.9 percentage points due to transformation, indicating that clients get more favorable interest rates. At the same time, MFIs are able to significantly cut down their operational expenses, of which 1.1 percentage points can be attributed to transformation. Other findings include a steep increase in commercial debt leverage and deposits, a significant decrease in the fluctuation of funding costs and a sharp rise in average loan size. Profitability goes down in the short and medium term, while return on equity is driven up in the medium to long run. By exploiting within-MFI data, our approach goes beyond previous studies that mainly relied on between-MFI data. Overall, the results suggest that transformed MFIs become an attractive environment for investors, potentially encouraging a more profit-seeking behavior among transformed MFIs.