Has the rise of passive investing broken the stock market? Is the level of passive ownership too high? No. There is no strong reason to believe that higher indexing degrades market efficiency. What matters are the non-passive investors: Are there enough of them, do they have the right incentives, are they able to express their views via trading? What does not matter are the passive investors: They are like the audience in a play; they just watch the activity on stage. There is no level of passive ownership, other than 100%, that obviously causes the market to be dysfunctional.
