The head of Arm’s China business, Allen Wu, has made a Rmb1.2bn ($179m) gain on a personal investment he made in one of the chip designer’s Chinese clients, after falling out with Arm over alleged conflicts of interest.

Mr Wu has been fighting Arm for control of the Chinese joint venture since June last year, when he disregarded a 7-1 vote by Arm China’s board to remove him. He remains Arm China’s legal representative and holds the company’s official stamp, making it difficult to dislodge him under a centuries-old Chinese system.

He is also in control of the company’s Chinese bank account, which holds $500m to $600m, and has been used to pay his legal fees for a court battle with its majority shareholders, Arm and Chinese partner Hopu Investments, according to two people familiar with the matter.