### Comment:
If you don't own every stock of the index how are you gonna track the index ? They are indeed obligated to own every single stock in the index. I’m not quite sure but I think they are allowed to decide the allocation them self. So for example they could have 100 AAPL and 1 SNAP for Nasdaq index fund.

### REPLY:
If it must track an index and to properly track its index then it must also allocate according to market size of said index?

### END.