One of Toshiba Corp.’s largest investors is calling on the conglomerate to run a strategic review after private equity firm CVC Capital Partners proposed taking the company private for $21 billion (¥2.3 trillion).

3D Investment Partners, which owns a 7.2% stake in Toshiba, said in a letter to the company’s board that it believes running a full and fair sales process was essential to rebuilding trust with investors after a tumultuous period that has included an investor revolt and the resignation of former CVC dealmaker Nobuaki Kurumatani as chief executive officer.

"To conduct a fair and proper process, Toshiba should explicitly indicate that it is open to alternative ownership structures and correct media speculation that Toshiba’s management team and board have a strong preference for remaining a listed company,” 3D Investment said in the letter, a copy of which was obtained by Bloomberg.