All-male boards in the US will see the UK’s biggest fund manager vote against them in a move to up the ante on boardroom diversity, according to a report in the Financial Times.

Clare Payn, head of governance in North America, is quoted by the FT as saying: “We feel there really should not be any all-male boards at this stage, as investors have been talking about this for so many years.”

The move comes as the latest statement on gender diversity in boardrooms, an area where many investors have said they will take a tougher stance this year.

Research published last year by the FT revealed that just 15% of boardroom positions in the US were held by women, compared with 25% in Europe.

In June last year the chair of the Securities and Exchange Commission, Mary Jo White, said diversity disclosure on top US boards needed to improve.

“As a former member of a public company board and its audit committee, I have seen first-hand what the research is telling us—boards with diverse members function better and are correlated with better company performance.

“This is precisely why investors have—and should have—an interest in diversity disclosure about board members and nominees.”

The FT says US companies with all-male boards include Coty, the beauty products maker; Dentsply, the dental product provider; and TransDigm Group, the maker of aircraft parts.