alt Hacker NewsThe flaw is the limited float. Indexes will be forced to buy a huge number of shares which don't exist, driving up the price.
For general investors if this is going to eventually happen, the earlier the indexes buy in the better. Otherwise more sophisticated investors will buy ahead of the indexes and grab the profit.
if they weighted (fully) by float (perhaps the average float from the trailing 90 days to the re-balance) it would not be as easy to game. The Nasdaq is accounting for float, but not completely.