The $1tn Norwegian sovereign wealth fund, which is the largest of its kind, has ramped up its efforts to improve corporate governance among companies it invests in. It has issued a set of recommendations around the practice of handing one person the roles of chair and chief executive.

The fund set out its position in three separate papers on Friday. One of its aims for the firms it invests in is to ensure the roles of chair and chief executive should be held by different people. Another recommendation was that board members of listed companies should not sit on more than five boards simultaneously.