An investment group led by private equity firm Alta Communications acquired the Yankee Group, a key research firm for tech industries, including the wireless industry. Emily Green became the new CEO of Yankee, replacing Brian Adamik who has stepped down from the top post. Green previously served as an executive at rival research firm Forrester Research and CEO at Cambridge Energy Research. Boston-based Yankee Group has 164 employees and claims 450 customers. The companies did not disclose financial terms of the agreement.