Microsoft appears to have scored a personnel win in the cloud wars, hiring former Amazon Web Services Senior Vice President Charlie Bell.

The move comes as Microsoft’s Azure cloud-computing wing continues to claw market share away from AWS, according to research firm Canalys.

Business Insider was first to report the news that Bell would join Microsoft. In Microsoft’s organization chart, Bell is currently listed as a corporate vice president in the human resources department, according to The Information, though it seems likely that he will ultimately land in a different role.

Amazon and Microsoft are currently negotiating over what Bell will be able to touch without violating the terms of his Amazon noncompete agreement, Business Insider reported. Amazon has previously sought to aggressively enforce noncompetes, especially for its former cloud-computing employees.

Bell did not respond to a request to confirm his career move. Amazon and Microsoft declined to comment.

Bell, who joined Amazon in 1998 when the company acquired his startup, began working in the then-nascent Amazon Web Services division in 2006, just as Amazon began marketing off-premises storage and computing power to the general public. He is widely credited with leading the development of AWS’ now vast line of cloud services.

Bell retired from Amazon this month, amid an exodus of senior leaders across the company. Among the high-profile resignations are those of Amazon’s physical retail czar Steve Kessel; Wei Gao, a grocery leader and former consigliere to Amazon founder Jeff Bezos; and worldwide consumer chief Jeff Wilke.

Kessel and Bell were both seen as possible picks to lead Amazon’s immensely profitable cloud-computing wing after the company announced this year former AWS chief Andy Jassy would replace Bezos as CEO.