Neil Levine, Canonical's VP of services, has quit the company and joined a small cloud systems management business.
The news comes after Matt Zimmerman, Canonical chief technology officer, also left the Ubuntu provider last week. In December, chief operating officer Matt Asay also left the company after just 10 months.
Levine has joined Soba Labs, a start-up, where he will be VP of product development.
During his two years at London-based Canoncial, Levine "ran the unit which built tools and delivered services to Ubuntu's enterprise customers", according to his LinkedIn profile. He was also responsible for server and cloud strategy.
At Soba Labs, he said, he aims to "bring the power of big data to cloud infrastructure management".
When Zimmerman announced his own departure from Canonical at the end of last week, he posted a message praising the Ubuntu and Canonical teams. "I am immensely proud of what we have accomplished together: bringing free software to people, places and organisations which have derived so much benefit from it," he said, adding that he would remain involved with the software.