Based on your financial expertise, provide your response or viewpoint on the given financial question or topic. The response format is open.

Is there any benefit to investing in an index fund?
when the index is altered to include new players/exclude old ones, the fund also adjusts The largest and (I would say) most important index funds are whole-market funds, like "all-world-ex-US", or VT "Total World Stock", or "All Japan".  (And similarly for bonds, REITS, etc.)  So companies don't leave or enter these indexes very often, and when they do (by an initial offering or bankruptcy) it is often at a pretty small value. Some older indices like the DJIA are a bit more arbitrary but these are generally not things that index funds would try to match. More narrow sector or country indices can have more of this effect, and I believe some investors have made a living from index arbitrage.  However well run index funds don't need to just blindly play along with this. You need to remember that an index fund doesn't need to hold precisely every company in the index, they just need to sample such that they will perform very similarly to the index.  The 500th-largest company in the S&P 500 is not likely to have all that much of an effect on the overall performance of the index, and it's likely to be fairly correlated to other companies in similar sectors, which are also covered by the index.  So if there is a bit of churn around the bottom of the index, it doesn't necessarily mean the fund needs to be buying and selling on each transition.  If I recall correctly it's been shown that holding about 250 stocks gives you a very good match with the entire US stock market.