Companies with women on their boards performed better in challenging markets than those with all-male boards in a study suggesting that mixing genders may temper risky investment moves and increase return on equity.

Shares of companies with a market capitalization of more than $10 billion and with women board members outperformed comparable businesses with all-male boards by 26 percent worldwide over a period of six years, according to a report by the Credit Suisse Research Institute, created in 2008 to analyze trends expected to affect global markets.

The number of women in boardrooms has increased since the end of 2005 as countries such as Norway instituted quotas and companies including Facebook Inc. added female directors after drawing criticism for a lack of gender diversity. The research, which includes data from 2,360 companies, shows a greater correlation between stock performance and the presence of women on the board after the financial crisis started four years ago.