This marks the most significant hire to date for CEO Marissa Mayer, who last month named Ken Goldman CFO. For this one she went back to her old stomping ground at Google to snatch Henrique de Castro, who was VP of Google’s worldwide Partner Business Solutions group, where he was responsible for advertising platforms and services for Google’s publisher and commerce partners. Before that, he helped grow Google’s media, mobile and platforms division. Here’s Yahoo’s release:

SUNNYVALE, Calif.–(BUSINESS WIRE)–Yahoo! Inc. (NASDAQ: YHOO) announced today that Henrique de Castro has been hired as chief operating officer (COO). Reporting directly to Yahoo! CEO Marissa Mayer, de Castro will be responsible for strategic and operational management of Yahoo!’s sales, operations, media and business development worldwide.

“Henrique is an incredibly accomplished and rigorous business leader, and I’m personally excited to have him join Yahoo!’s strong leadership team”

“Henrique is an incredibly accomplished and rigorous business leader, and I’m personally excited to have him join Yahoo!’s strong leadership team,” said Marissa Mayer, CEO of Yahoo!. “His operational experience in Internet advertising and his proven success in structuring and scaling global organizations make him the perfect fit for Yahoo! as we propel the business to its next phase of growth.”

“The combination of Yahoo!’s unique properties with high quality content, its renewed focus on outstanding user experience and its massive reach bring tremendous value to users, advertisers and partners,” said de Castro. “This is a pivotal point in Yahoo!’s history, and I believe strongly in the opportunity ahead. I can’t wait to join Marissa and the team and get started.”

De Castro brings more than 20 years experience leading operations, strategy, partner management and revenue generation for some of the world’s leading brands. Most recently, he was vice president of Google’s worldwide Partner Business Solutions group, where he was responsible for advertising platforms and services for Google’s publisher and commerce partners. Prior to that, he led Google’s media, mobile and platforms organization, where he helped to grow the business significantly. Prior to Google, de Castro spent two years at Dell Corporation, where he managed sales and business development operations across Western Europe. He has consulted for McKinsey & Company, where he advised numerous clients across many different industries. His career also includes senior positions in private equity and advertising businesses.

De Castro will join the company on or before January 22, 2013, or as soon as he has satisfied his obligations to his current employer.

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