Want to Boost Shareholder Returns? Hire a Woman

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Firms with at least one woman on their executive board generate greater returns for shareholders, a new study has found, bolstering the argument that gender equality is better for business.

In a survey of 50 North American and U.K. companies, PA Consulting Group found that those with females on their board boasted higher total shareholder returns (TSR) over a six-year period.

"These 50 organizations demonstrate that the presence of women in senior positions only serves to increase the organization's culture and performance… it is absolutely in companies' best interests to raise their game when it comes to promoting gender diversity," said the PA report.

(Read More: Why Women Make Boardrooms Better)

PA found that companies with at least one woman on their board generated up to 600 percent TSR during this time period, while those with none made a maximum of 100 percent.

However, PA cautioned businesses not to rush to recruit external female talent.

"It is very tempting to think that the quickest solution to the challenge of raising the percentage of senior female leaders is to 'buy' the talent from outside. Although this might seem like an immediate solution to the problem, our research shows that those organizations with a higher percentage of internal appointments within their executive committee demonstrate a much higher total shareholder return. So the injection of external female talent may solve the short-term problem, but may not drive sustained performance over time," the report said.

(Read More: More Women in Boardrooms? Campaigner Says Progress Being Made)

According to PA, 15 percent of North American companies listed on the FTSE All World Developed Index have no women on their boards, compared with 46 percent of U.K. companies on the FTSE All Share Index, and 73 percent of companies in the Asia-Pacific region.

"Despite decades of well-meaning interventions, and in the face of incredible pressure from society, many companies have had limited success in accelerating women up the management ladder," said Lesley Uren, PA talent management expert, in the report.

By CNBC's Jenny Cosgrave: Follow her onTwitter @jenny_cosgrave