Riot announced the sale of its remaining equity in an oblique message on its website framed as a cash-based incentive program for Riot employees:
As a result of our continued growth and changing circumstances, we’re shifting to a new structure to recognize and reward Rioters’ contributions – and that first involves a big change to our existing equity program. As part of this effort, our majority investor, Tencent, recently purchased the remaining equity of Riot Games. This allows us to move away from a Riot equity program towards a cash based incentive program that allows Rioters to share in Riot’s success. This program comes in addition to our highly competitive salaries, open PTO, learning and development programs, 401K match, subsidized medical plans, and kitchens stocked with snax (poro and otherwise) all full-time Rioters get.
Tencent’s major purchases of Riot came in 2008 and 2011. The company also has a small stake in Epic Games.