Improving access to quality-assured artemisinin combination therapies (ACTs) is an important component of malaria control in low- and middle-income countries. In 2010 the Global Fund to Fight AIDS, Tuberculosis, and Malaria launched the Affordable Medicines Facility--malaria (AMFm) program in seven African countries. The goal of the program was to decrease malaria morbidity and delay drug resistance by increasing the use of ACTs, primarily through subsidies intended to reduce costs. We collected data on price and retail markups on antimalarial medicines from 19,625 private for-profit retail outlets before and 6-15 months after the program's implementation. We found that in six of the AMFm pilot programs, prices for quality-assured ACTs decreased by US$1.28-$4.34, and absolute retail markups on these therapies decreased by US$0.31-$1.03. Prices and markups on other classes of antimalarials also changed during the evaluation period, but not to the same extent. In all but two of the pilot programs, we found evidence that prices could fall further without suppliers' losing money. Thus, concerns may be warranted that wholesalers and retailers are capturing subsidies instead of passing them on to consumers. These findings demonstrate that supranational subsidies can dramatically reduce retail prices of health commodities and that recommended retail prices communicated to a wide audience may be an effective mechanism for controlling the market power of private-sector antimalarial retailers and wholesalers.