MM'S25 Aug 2009 13:39
A brokerage that maintains a firm bid and ask price in a given security by standing ready, willing, and able to buy or sell at publicly quoted prices (called making a market). These firms display bid and offer prices for specific numbers of specific securities, and if these prices are met, they will immediately buy for or sell from their own accounts. Market makers are very important for maintaining liquidity and efficiency for the particular securities that they make markets in. These trade can be made in seconds and of course they can manipulate prices depending on how much stock they hold or simpy cause movement by changing prices.