A trading platform, otherwise known as an online brokerage account, allows you to buy and sell investments via computer or mobile app. The brokerage holds your investments and deposited cash for you and provides activity reports and account statements. It also credits any interest accrued and dividends to your account. To open an online broker account in the United States, you will need a Social Security number and you will be required to enter basic financial information such as your name, address, phone number, and trading experience. In the United States, brokers are regulated by both FINRA and the SIPC. The SIPC insures $500,000 per account including up to $250,000 in cash against theft or the firm going belly-up. It’s important to remember, however, that insurance does not protect any investor against losses due to market fluctuations.