Chip designer Arm Ltd .’s China joint venture could be acquired by a firm whose origin is shrouded in mystery, in the latest chapter of a two-year boardroom struggle with ousted Chairman and CEO Allen Wu. In a statement published last week, the firm in question — Lotcap Group — said that it had signed a letter of intent to buy a 51% stake in Arm China from Chinese shareholders Amber Leading (Hong Kong) Ltd., Ningbo Meishan Bonded Port Area Anchuang Growth Equity Investment Partnership, and Arm Ecosystem Holdings (Hong Kong) Ltd.