Art Technology Group Added to Russell 3000 -R- and Russell 1000 -R-.

Business/Technology Editors

CAMBRIDGE, Mass.--(BUSINESS WIRE)--July 12, 2000

Art Technology Group, Inc. ("ATG") (Nasdaq:ARTG) today announced that it has been added to the Russell 3000(R) and the Russell 1000(R) indexes. Published by the Frank Russell Company, these indexes are updated each year on May 31 and rank the 3,000 and 1,000 largest companies on the U.S. stock market.

"We are very proud of ATG's numerous operational and financial accomplishments during its first year as a public company," stated Jeet Singh, chief executive officer of ATG. "Even more rewarding, however, has been the recognition that we continue to receive from our customers, partners and industry peers. The addition of ATG to the Russell 3000 and Russell 1000 is yet another success - one that we owe to the steadfast support of our shareholders. We expect that the company will benefit from this increased visibility going forward."

The Russell 3000 Index measures the performance of the 3,000 largest public companies listed on U.S. stock exchanges, based on total market capitalization. The Russell 1000 measures the performance of the 1,000 largest companies in the Russell 3000 Index. The Russell 1000 and the Russell 3000 are leveraged as performance benchmarks by which many institutional and individual investors base their buying and selling decisions.

ATG completed its successful IPO on July 21, 1999, a follow-on offering on November 10, 1999 and a two-for-one stock split on March 27, 2000. In the first quarter of 2000, the company reported total revenues of $21.6 million, a 391 percent increase over the $4.4 million reported in the first quarter of 1999. ATG's customer roster now includes more than 350 companies and its partner list now exceeds 150 corporations worldwide.

About ATG

Art Technology Group, Inc. is a leading provider of Internet customer relationship management and electronic commerce products and services. ATG offers an integrated suite of Java application server-based products and services, as well as related application development, integration, and support services. The ATG Dynamo(R) Product Suite enables Global 1000 enterprises, as well as new businesses using the Internet as their primary business channel, to understand, manage, and build their online customer relationships and to more effectively market, sell, and support their products and services over the Internet.

The Dynamo solution is designed to provide businesses with the core platform and software tools required to develop and deploy personalized, scalable, and reliable e-commerce Web sites. Dynamo is licensed to over 300 customers including 3M, BabyCenter, BMG Direct, Eastman Kodak, Informix, Network Solutions, Sun Microsystems, and TheStreet.com. The company is headquartered in Cambridge, MA, with additional locations throughout North America and Europe.

This press release contains forward-looking statements for purposes of the safe harbor provisions under The Private Securities Litigation Reform Act of 1995. These statements involve known and unknown risks and uncertainties that may cause ATG's actual results, levels of activity, performance or achievements to be materially different from any future results, levels of activity, performance or achievements expressed or implied by such forward-looking statements. Important risk factors affecting ATG's business generally may be found in most recent 10-K and in periodic reports and registration statements filed with the Securities and Exchange Commission. Risk factors related to the subject matter of this press release include the possibility that the company will not continue to increase its visibility; that the partner and customer lists will decline in the future; and the costs and risks associated with intellectual property infringement and litigation. ATG undertakes no obligation to update any of the forward-looking statements after the date of this press release.