Prior to its merger with Ameritrade Holding Corporation, TA invested in Datek Online Holding Corp., a provider of financial technology products and services to the institutional and retail trading communities, and a pioneer in the online brokerage industry.

In September 2002, Datek merged with Ameritrade Holding Corporation (NASDAQ: AMTD), uniting two firms that had the lowest cost operations and highest operating margins in the online brokerage industry, and forming the largest online equity trading business.

Ameritrade acquired TD Waterhouse in 2006, and was renamed TD Ameritrade.