A rm Holdings Plc’s Chinese venture have started a chip design house with local government backing, adding to uncertainty in the British firm’s biggest market just weeks after it raised $5 billion in an initial public offering. The departures from Arm China included the head of R&D, a regional head of sales and a government relations employee who is now chief executive officer of the new firm, Borui Jingxin, people familiar with the matter said. The two-and-a-half-year- old firm is backed by Shenzhen’s government and aims to raise capital and recruit engineers — including from Arm. Borui is also a...