NEW YORK (AP) -- Viggle, which operates an app that tracks TV and music habits in exchange for rewards, on Friday filed for an initial public offering of common stock.

The company didn't say how many shares it plans to sell. It said the IPO would take place "as soon as practicable."

The company's stock is currently traded on the Pink Sheets -- a platform that allows people to buy shares but doesn't require the company to release its financial results -- under the symbol "VGGL." Viggle plans to apply to list the new shares on the Nasdaq Stock Market.

About 80% of the company's Pink Sheet shares are currently held by entertainment entrepreneur Robert F.X. Sillerman, the company's chairman and CEO, along with other company executives.

According to the filing, Sillerman plans to buy some of the new shares and maintain a stake in the company, but the filing didn't say how many.

Viggle produces smartphone and tablet apps, which debuted about two years ago, that allow users to check in when watching TV or listening to music. The apps work by using the smartphone or tablet's microphone to determine what the person is watching or listening to through sound.

Users earn points depending on how long they watch or listen and the points can be traded in for rewards like gift cards. Bonus points can be earned by watching certain promoted shows or advertisements.

From its January 2011 launch to Sept. 30, 2013, a total of 3.5 million users registered with Viggle. Of that number, 200,224 have deactivated their accounts for a net 3.3 million registered users. For the three months ended Sept. 30, 2013, the company had 474,796 monthly active users.