Alternative Trading Systems (ATSs) are electronic trading platforms that connect buyers and sellers of securities that do not take place on traditional stock exchanges. ATSs are typically operated by broker-dealers and are subject to Securities and Exchange Commission oversight (SEC). Dark pools and electronic communication networks are examples of ATSs (ECNs). ATSs can offer a variety of advantages, including increased liquidity and lower transaction costs. They can also provide traders with access to a broader range of securities and provide an alternative way for businesses to raise capital. However, there are concerns that ATSs could be used for insider trading or other forms of market manipulation.