TD Ameritrade (AMTD) took the big step of launching the Investor Movement Index, or IMX, earlier today. This innovative tool will give investors another way to track investor sentiment. The IMX will serve as a snapshot of actual portfolio activity from the more than 6 million TD Ameritrade clients. It is a proprietary, behavior-based index, which uses data from one of the largest pools of American retail investors to gauge how bullish or bearish American investors are about the markets.

Steve Quirk, senior vice president of TD Ameritrade’s trader group, said that the company saw an opportunity to track what investors are actually doing with their money, and gauge how they respond to market events. Quirk said, “The purpose of the Investor Movement Index is to harness our vast amount of retail clients behavior data to show, over time, how this group reacts to market events.” He also noted, “TD Ameritrade is proud to be the first and only firm to look at investor sentiment in this new way.”

The first official Investor Movement Index data is for December 2012. The score for the month of December was 4.94, and the trend direction is positive. Compared to historic ranges this is a moderately high number. In addition to the new data from December, past IMX scores are also now available all the way back to January 2010. The monthly data will be released by TD Ameritrade between the 6th and 8th business day of the following month.

The Investor Movement Index is a tool that should help investors get a much more complete view of retail investor sentiment.

For more on this new index click here.