Microsoft CEO Satya Nadella (C) listens to Amazon CEO Jeff Bezos during an American Technology Council roundtable at the White House in Washington, DC. Nicholas Kamm | AFP | Getty Images

When Ruhi Sarikaya, Amazon’s director of applied science, spoke at the World Wide Web conference in April, an Echo device on stage introduced him as the person “building my brain.” Then it shared a fun fact about his previous job: he founded a key group within Microsoft’s Cortana voice-assistant team. “His group has built language understanding and dialog management capabilities of Cortana,” the Echo said. Sarikaya, who spent five years at Microsoft before joining Amazon in 2016, now leads a team of over 200 engineers for Alexa Brain, according to a person familiar with the matter. His team is responsible for building the core AI technology for Alexa’s natural language processing and dialog management, among other key capabilities, his LinkedIn profile says. Besides the irony of one person building the same core technology of two competing products, Sarikaya’s jump to Amazon highlights a broader hiring trend: Amazon’s penchant for poaching Microsoft executives. In fact, Amazon has hired more executives from Microsoft than from any other tech giant in recent years, according to Paysa, a startup that collects and analyzes work salary information.

In the three years between 2015 and 2017, at least 30 director or higher level executives went straight from Microsoft to Amazon. Google, the next most popular poaching ground for Amazon, lost just 5 executives to the e-commerce company during those three years. Apple and eBay both lost 2 executives to Amazon in that period, while Facebook, Walmart, and Netflix saw zero executives go to Amazon. Paysa’s data only includes people whose most recent jobs were at Microsoft and excludes the ones who may have worked elsewhere before joining Amazon. The company said it looked through at least 5 million resumes for this data, but may have missed the ones that did not update their resume profiles. Many of the Microsoft transplants now sit in the highest ranks at Amazon. For example, VP of eCommerce services Dave Treadwell, who spent over two decades at Microsoft, joined Amazon in 2016 and now reports directly to Jeff Wilke, CEO of Worldwide consumer. Marc Whitten, former chief product officer at Microsoft, is now a VP reporting directly to Amazon’s hardware chief Dave Limp. Dirk Didascalou, Amazon’s VP of Internet of Things, was most recently a corporate VP leading Microsoft’s Surface Hub group. Amazon declined to comment on this story. Microsoft’s representative wasn’t immediately available for comment.