An activist group called Walmart 1 Percent released a report today which makes a persuasive case that the megastore company’s four surviving heirs have donated a staggeringly low amount of money to charity relative to their wealth.

Specifically, the report found that the heirs have given only 0.04 percent of their $140 billion fortune to their own family’s charity and that two—Rob and Alice Walton—have never given money to the foundation at all. The figure is especially striking in comparison to the donations made by Walton-family peers like Bill Gates and Warren Buffett:

The report says its authors could find no evidence of significant giving by the Walton heirs to other charities, and a family spokesperson’s statement to Forbes about the report did not cite any examples of giving to outside groups.

The heirs’ parents (including company founder Sam Walton) and late brother gave around $5 billion to the Walton Family Foundation. But the Walmart 1 Percent report and this Bloomberg piece say those donations were made through trusts that could allow the heirs to end up personally inheriting more money than they would have if their parents and sibling had given no money to charity at all. (And the Walton Family Foundation is still fairly small compared to other groups associated with mega-wealthy familes.)

(For further explanation of the estate-tax/trust stuff, click here. The Walton trusts in question are CLATs, which are openly advertised by financial services firms as a way of passing on money to your heirs while avoiding taxes.)

h/t Gawker