ATG Announces Gross Proceeds of $100.6 Million

CAMBRIDGE, Mass.–(BUSINESS WIRE)– ATG (Art Technology Group Inc., NASDAQ: ARTG) today announced that the underwriters of its public offering exercised their option to purchase an additional 3,750,000 shares of common stock to cover over-allotments. Deutsche Bank Securities Inc. and Morgan Stanley & Co. Inc. are acting as joint book-running managers and underwriters for the offering.

On Friday, February 5th, ATG announced a public follow-on offering of 25,000,000 shares of its common stock at $3.50 per share. Taking into account the full exercise of the option to purchase additional shares, total gross proceeds are expected to be approximately $100.6 million. The offering is expected to close on February 10, 2010.

ATG filed a shelf registration statement on Form S-3 relating to the securities described above with the Securities and Exchange Commission on November 2, 2009, which became effective on November 18, 2009. This press release does not constitute an offer to sell or a solicitation of an offer to buy the securities described herein, nor shall there be any offer, solicitation or sale of these securities in any state or jurisdiction in which such an offer, solicitation or sale would be unlawful.

To obtain a copy of the final prospectus for this offering, please contact Deutsche Bank Securities Inc., Attention: Prospectus Department, 100 Plaza One, Jersey City, New Jersey 07311, Telephone: (800) 503-4611; or Morgan Stanley & Co. Inc., Attention: Prospectus Department, 180 Varick Street, Second Floor, New York, New York 10014, Telephone: (866) 718-1649, email: prospectus@morganstanley.com.

About ATG

ATG is a global specialist in e-commerce. ATG Commerce is a commerce platform and business user application solution designed to power personalized, efficient and effective e-commerce sites. ATG’s platform-neutral optimization services can be added to any Web site to increase conversions and reduce abandonment. These services include ATG Recommendations and ATG’s live help services, including ATG eStara Click to Call, and Click to Chat. The company is headquartered in Cambridge, Massachusetts, with additional locations throughout North America and Europe.

© 2010 Art Technology Group, Inc. ATG and Art Technology Group are registered trademarks. All other product names, service marks, and trademarks mentioned herein are trademarks of their respective owners.