Want to outperform? Put women on your board

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As European politicians push for more women on the boards of top companies, a recent survey shows that female directors can actually help a firm's stock price.

The study "Mining the Metrics of Board Diversity" conducted by Thomson Reuters involving 4,100 companies showed that shares of firms that had mixed-gender boards matched or outperformed the MSCI World Index over the past 18 months, compared to company boards that had only men. The MSCI World Index has risen 23 percent since about mid-January 2012.

"This study reinforces the idea that gender equality in the workplace makes good investment and business sense," Andre Chanavat, product manager, Thomson Reuters environmental, social & governance, said in a note.

The report released on Wednesday also showed that companies with women on their boards had less tracking errors, which means their stock price followed the benchmark index more closely, indicating less volatility.

(Read More: EU Aims to Get 40% of Top Positions Filled by Women)

While there have been significant measures put in place in the last five years to increase the number of women on the board of companies, Chanavat said there is still a long way to go in increasing equal opportunity and diversity globally.

For example, the number of companies surveyed that have adopted policies and processes to promote gender diversity and equal opportunity increased only 2 percent to 66 percent from 2008 to 2012, according to the study. Meanwhile, the percentage of companies that have women on their boards rose from 56 percent in 2008 to 59 percent in 2012.

The biggest increase came in the number of companies that reported having a board consisting of 10 percent or more women, which jumped to 45 percent in 2012 from 39 percent in 2008.

(Read More: Want to Boost Shareholder Returns? Hire a Woman)

Globally, European, Middle Eastern and African companies had the most women on their boards, followed closely by the Americas, while firms in the Asia-Pacific region had the least gender-diverse boards.

In terms of industries, technology, industrials and non-cyclical consumer goods and services sectors lead in having more women on their boards, while healthcare companies have the least.

By CNBC.com's Rajeshni Naidu-Ghelani; Follow her on Twitter @RajeshniNaidu