Companies that have female directors out perform those that only have men.

A Credit Suisse report found that, overall, companies with a market cap greater than US$ 10 billion that have at least one woman on the board of directors outperformed those that had no women at all by 26% for large caps over the six years leading up to 2011.

"Importantly, this mix of companies would also have outperformed global equities as measured by MSCI’s ACWI," write Credit Suisse analysts Julia Dawson, Richard Kersley and Stefano Natella.

In other words, this is a global phenomenon.

From 2012 to June 2014, companies with at least one woman on the board have seen a 5% outperformance on a sector neutral basis.

That amounts to a compound excess return since 2005 of 3.3%.

Credit Suisse

Countries in the Asia-Pacific saw the greatest outperformance with a 55% excess cumulative return. That's a huge number.

Credit Suisse

They were followed by the US, which saw 20% outperformance, also a significant amount.

Credit Suisse

And third in Europe, which had 18% outperformance.