Just simply opening an account with TD Ameritrade doesn’t mean you’re able to... 2. The equity required to maintain your short position may vary based on the market price of the security you shorted, and if the short position moves against you your account could face a margin call, requiring you to deposit additional funds. During our testing, we found the simplest method to establish a short position was to right-click on a chart and select sell from the drop-down menu. TD Ameritrade’s desktop platform can be used to establish short positions on any of the products discussed above. 7 Steps to Shorting a Stock (With TD Ameritrade as an example) 1. Enable Your Account for Margin Trading In order to short sell on TD Ameritrade, you must have a margin-enabled, non-retirement account with at least $2,000 in marginable equity.