The US Securities and Exchange Commission is investigating SoftBank and former exec Nikesh Arora, following disquiet among shareholders.

According to The Wall Street Journal, a lawyer representing “disgruntled investors” said Arora was aware of the watchdog’s move. Arora, who was president and CEO of the Japanese company, stood down after Masayoshi Son, chairman and CEO, indicated he intends to remain at the helm for another five to ten years – and Arora had been heir apparent.

AroraShortly before Arora’s departure, SoftBank said that a special committee it set-up to review “allegations” regarding the executive’s conduct had found the claims were “without merit”.

At the heart of the disquiet is SoftBank’s somewhat lacklustre investment strategy, which came under Arora’s remit. The executive’s role as an advisor to private equity firm Silver Lake has also been suggested as a conflict of interest.

Financial Times suggested that Arora’s departure came after a split with Son which “went deeper than a succession clash”. Arora apparently irked Japanese staff with his “distant management style” as he made a number of investments in international markets.

And SoftBank has also made a number of recent moves to exit or reduce its stake in affiliated companies. It is selling its stake in games makers Supercell (to Tencent) and GungHo Online Entertainment, and is cutting its stake in Chinese e-commerce giant Alibaba.