TD Ameritrade Institutional is a division of TD Ameritrade, Inc., a brokerage subsidiary of TD Ameritrade Holding Corporation. TD Ameritrade, Envestnet and the other entities named are separate and unaffiliated firms, and are not responsible for each other’s services or policies. Thinkorswim - Wikipedia Thinkorswim by TD Ameritrade (often stylized and officially branded as "thinkorswim", lacking capitalization) is an electronic trading platform by TD Ameritrade used to trade financial assets.It is geared for self-directed stock, options and futures traders. It was previously offered by ThinkorSwim Group, Inc., which was purchased by TD Ameritrade in 2009.