Bill Stasior, the longtime former Apple executive overseeing its Siri digital assistant, has joined Microsoft, continuing a reshuffling of artificial intelligence leadership at big tech companies. 

Starting this month, Stasior, whose move to Microsoft hasn’t been previously reported, will become a corporate vice president of technology, reporting to Chief Technology Officer Kevin Scott. Stasior referred questions about his new job to a Microsoft spokesperson, who confirmed Stasior’s hiring, adding that “he will work to help align technology strategies across the company.” At Microsoft, Stasior will lead an artificial intelligence group, a person familiar with the matter said.

The shift underscores the intense demand for AI leadership inside the largest tech companies, all of which are jockeying for position against each other. Last year, Apple recruited a prominent Google executive, John Giannandrea, to lead AI strategy. Stasior reported to Giannandrea.