Royal Decree 1766/2007, passed at the end of 2007, has changed the regulations concerning the obligation to maintain minimum security stocks of hydrocarbons and diversification of natural gas supplies in Spain. The modifications regard the volumes required, the authorized location, and the mechanism to compute them. This article from Gas Actual reviews the content of the new legislation and how it fits the new fully-liberalized gas market model, where transport and distributor operators no longer develop supply activities and have lost their role in ensuring security of supply for the Spanish gas market.