Let's model an equal-weighted index with nine components, with each thus representing 1/9th of the index's allocation.
You learn that a tenth member is going to be added. You don't know who it is. But you know that each of those nine will, after that member is included, represent 1/10th of the index's allocation versus the 1/9th they did before. You know a precise bucket of trades everyone following the index is going to mechanically enter into. Which means it behooves you to be on the other side of it.
When rebalancing–or new inclusion–occurs, you see this pre-trading. Similar to merger arb. But much more clear as a signal because you see it in precise ratios across the index's members. It's difficult to pick up for small indices. But for something like the S&P 500, you'd expect to see someone selling those shares in anticipation, and, now that the rule isn't going into effect, someone dumping those shares in those ratios.
It would be visible at a macro level, you’d see a higher sell volume and probably a drop in price as all the equal weight funds rebalance.
There’s a heavy motivation to be the first mover here, because those sells will cause a supply spike and price drop. By being the first mover, you can rebalance before prices drop.
I don’t have sell volume data, but we didn’t see price drops so either a) the market did not believe and no one rebalanced, or b) few funds rebalanced, and the other funds disbelieved enough that they thought the risk premium was so small they could buy at a slight discount and profit, balancing supply and demand.
Would you see funds reducing their equity exposure and going into cash or what? Which funds would do that? Trackers wouldn’t do that so where would you see that withdrawal of funds?
> New entrant means you have to pull money out of existing stocks to re-allocate to the new entrant to maintain equal weights.
If you mean someone tracking an equal weight index the weights would be essentially the same after the inclusion of SPCX replacing some other constituent. Except for the stock being replaced, of course.