Macro Trends, page-215

I haven't read the article, but i suspect if you looked at the data it would be because Large corporates are under more pressure to have females in positions of power. Smaller companies can get away with whatever racial/gender mix they want, that's why the figures look distorted. Not saying female CFO's are bad, just that the stats aren't as meaningful as they may appear.

Again, haven't read the article or data, but I have a natural skepticism towards these things.