Here are a couple of recent links from me on this here and here.

There was one sentence that made me laugh out loud: “Passive investors who want to avoid the overconcentration risk from cap-weighted indexes can buy funds that own equal proportions of each stock in an index …” The idea may be perfectly valid but it is clear to me that the person who decides to switch to an index fund that uses an alternative weighting process is not a passive investor, they are making a very active decision, using what might be a passive vehicle to do it.

I've been saying for a long time that the active/passive debate has become the wrong thing to look at, it isn't even a thing. My take has been that what “passive” investors really are is users of passive funds and not very active. Rebalancing is an active decision. What threshold causes you the passive investor to rebalance? No matter the answer it is an active decision. What is your asset allocation? That is an active decision. Leave the labels behind, use whatever you think are the best vehicles for the exposures you want and when possible, use a less expensive option where there is more than one choice for an identical exposure.