BlackRock and Vanguard, giant managers of exchange traded funds and other passive-style investments, are the biggest owners of publicly traded firearms makers like Sturm Ruger and American Outdoor Brands. That’s because these funds track stock indexes that include the stocks of the gun makers.

BlackRock recently said it had created new funds that would exclude those stocks for investors that wanted to avoid owning them. The fund manager has also said it is in active conversations with gun makers about their businesses.