Carol Hymowitz and Cécile Daurat write for Bloomberg that if you look at the five top-paid executives at each of the S&P 500 companies you find that only 8 percent are women, and the women earn 18 percent less than the men in the sample. They also offer specific examples of woman executives like Denise Morrison (CEO of Campbell Soup), Heather Bresch (CEO of Mylan), Kimberly Dang (CFO of Kinder Morgan), and Mary Winston (CFO of Family Dollar Stores) who appear to be paid substantially less than men with comparable roles at firms in the same industry sector.
When I wrote about the arbitrariness of CEO pay with respect to international comparisons I ended up getting dragged into the tedious debate over whether CEOs are "overpaid" or not. That's a topic that combined extremely strong ideological priors with a total lack of well-defined concepts. What you see by adding gender into the picture is just that, once again, pay seems a bit all over the map. There's no market-clearing wage for executive compensation, and firms do not in practice seem very interested in bargain hunting.