Index providers definitely own their trademarks. You can’t market an S&P index without paying S&P. But “the available authority indicates that copyright protection for indexes may extend to the index constituent lists but not index averages, and copyright preemption principles may limit misappropriation protection for indexes to a very narrow class of ‘hot news’ uses” [1].

> you'd only get a license when accepting their terms

Sure. But plenty of indices allow for mixing and matching. The terms are designed to avoid confusion—you can’t use the term NASDAQ 100 if it isn’t exactly that. More broadly, there are tons of indices and benchmark portfolios.

[1] https://www.blegalgroup.com/market-index-licensing-a-review-...

How is this a response?