From the IRS statistics of income (these really are just fascinating data sets), we get the
personal wealth statistics, which show a pretty big gender gap at the very top of the top (but perhaps not as much as one might expect just underneath):
Female vs Male Top Wealth Holders by Size of Net Worth, numbers in millions, source IRS SOI Personal Wealth Stats (2012).
What this chart shows is that among those with estates suggesting net wealth of over $20m, men have a net worth that's double that of women (2,638,888,000 vs. 1,323,051,000); but look at the 3.5 to 5 million bracket, there the net worths are much closer together (784,506 vs. 726,538).
These numbers are estimated based on estate tax returns; from the website:
"The Personal Wealth Study uses information reported on Form 706, United States Estate (and Generation Skipping Transfer) Tax Return, to estimate the wealth of the living population. These estimates, based on the Estate Multiplier technique, appear every three years. The estimates are limited to that segment of the population for whom personal wealth is at least equal to the estate tax filing threshold in effect for the estimation period."
To go along with the amount gap, though, let's add how many people are in each category:
At the very top, men outnumber women 2.6 to 1 (324,000 to 125,000). (These numbers are in thousands, according to the IRS website). Is that really right, are there really 324,000 men and 125,000 women in America, each of which have a net worth exceeding $20 million? That seems amazing--I don't think I know any.