Résumé : Recent evidence shows that the poor desperately need access to savings products. But despite this general consensus, microfinance institutions (MFIs) offering savings products are still under-studied. Using random-effect probit estimation on a dataset of 722 MFIs active over the 2005-2010 period, we try to identify the characteristics of those that collect voluntary savings. Our results suggest that these MFIs have received fewer subsidies than their credit-only counterparts. In other words, subsidies would crowd out micro-savings products, suggesting that donors generate negative externalities on product diversification.