@alta12 schweser practices exam are pretty similar to the previous years, they made minor changes here and there, just briefly compared it to my friend’s practice mocks so they might have left this out. Plus, schweser made their errata section private now.
@alta12, I too did not find this statement. However since using free float Market cap is correct procedure I have selected it as right. May be it was in old syllabus and they missed to correct it.
I have not seen this statement anywhere in the books (or maybe I don’t remember it). I can confirm from work experience though that there are GDP-weighted indices out there.