From the DoubleClick press release:
GOOGLE TO ACQUIRE DOUBLECLICK
Combination Will Significantly Expand Opportunities for Advertisers, Agencies and Publishers and Improve Users’ Online Experience
Mountain View, CA, 4/13/2007 – Google Inc. (NASDAQ: GOOG) announced today a definitive agreement to acquire DoubleClick Inc., a global leader in digital marketing technology and services, for $3.1 billion in cash from San Francisco-based private equity firm Hellman & Friedman along with JMI Equity and management. The acquisition will combine DoubleClick’s expertise in ad management technology for media buyers and sellers with Google’s leading advertising platform and publisher monetization services.