what is an open end index fund 
an open end index fund is an open end fund that tracks a specific index an open end index fund selects a benchmark to track such as the s p 500 and purchases the stocks in that index in order to replicate its returns an open end index fund is different from an exchange traded fund etf which also tracks an index in that it has characteristics reflective of an open end fund such as being priced to its nav once a day and only being able to be purchased and sold once a day 