The over-the-counter market is a decentralized market in which unlisted securities trade.The OTC market is not a physical location. Prices are negotiated, and trades are made through computer networks, phones and email. Dealers act as market makers, and quote prices at which they will buy and sell. OTC markets usually have both a customer market, where dealers trade with corporations and institutions, and an interdealer market where dealers trade with each other. Thousands of unlisted securities trade on the OTC market. They are often small companies who don’t meet the requirements to be listed on exchanges such as the New York Stock Exchange. They are considered more risky than exchange-traded stocks. OTC markets are less transparent than exchanges, and subject to fewer regulations. Trades can be quietly made between two parties without others knowing the price. The OTC market’s lack of transparency can cause problems. During the 2008 financial crisis, mortgage-backed securities and other derivatives that traded solely in the OTC markets could not be reliably priced. As a result, buyers stopped buying. Liquidity dried up, and dealers withdrew. The liquidity problem grew worse, resulting in the worldwide credit crunch.