BOSTON (AP) — Index mutual fund investors are a cost-conscious bunch. Rather than seek out managers with a good shot at beating the market, they parse tiny differences in fund expenses. Index funds are cheaper because no one is being paid to pick stocks. Every cent that doesn’t end up in someone else’s pocket counts, the thinking goes.

If that’s your mindset, you’ll want to pay attention to an aspect of index fund expenses that’s drawing greater scrutiny: fees that fund companies pay to license benchmark indexes.