There are two types of public stocks that can influence prices, namely buffer stocks and social safety net stocks (dependent on their size and operation). Emergency stocks have no impact on prices since they are only released to respond to humanitarian emergencies and the stocks held are usually not sufficiently large so that acquisition or disposal of stocks has any significant price effects on markets. Buffer stock programmes influence prices directly as they aim to stabilise prices and/or alter the level of producer and consumer prices. Social safety net stock schemes aim to assist the impoverished and chronically food insecure by distributing food at subsidised prices.