(Reuters) - SoftBank Group's Michael Ronen, the U.S. head of its $100 billion Vision Fund, is leaving after expressing concerns about "issues" at the technology conglomerate, the Financial Times reported on Tuesday. Ronen, who joined SoftBank in 2017, has been negotiating the terms for his departure for several weeks, the report https://www.ft.com/content/29b4d990-4770-11ea-aeb3-955839e06441 said.A managing partner at SoftBank Investment Advisers, Ronen was in charge of sourcing deals, making..