Santa Monica car sales portal TrueCar Inc. announced in a Monday SEC filing that it plans to sell 6.4 million shares in a secondary offering. The company itself will issue 1 million shares of common stock, while existing shareholders will unload the remaining 5.4 million.

Selling shareholders include most of TrueCar’s biggest investors, including San Antonio insurance and financial services firm United States Automobile Association. The company is selling 3 million TrueCar shares but will remain the Santa Monica firm’s biggest shareholder.

Also selling shares are venture capital investors Anthem Venture Partners of Santa Monica, Vulcan Capital of Seattle and Beverly Hills billionaire Jeff Skoll’s Capricorn Investment Group. All three will retain the vast majority of their TrueCar shares.

According to the filing, TrueCar Chief Executive Scott Painter has indicated an interest in purchasing up to $500,000 of stock in this offering. However, he is under no obligation to do so.

The company also announced plans for a roadshow to promote the offering.

TrueCar had its initial public offering on May 16, when the company raised $70 million with its shares priced at $9. TrueCar, which trades on the Nasdaq under the symbol TRUE, closed at $16.56 a share in Monday’s trading.