Some thoughts on index funds & market efficiency (including some empirical material)
Currently there are a lot of articles in the financial press about the perceived “fight” between active and passive asset management styles.
The passive guys make the point that on average, after fees, active funds have to underperform against the index and low-cost index funds, which is difficult to counter. On top of that, “alpha” created by large active funds is not very persistent.
From the active side, there is the argument that if there is too much money invested in index funds, market efficiency will suffer and stocks will go up and down together because not enough people are analyzing single stocks. If stocks go up and down together without reflecting fundamentals, at some point in time “good stocks” should be too cheap and bad stocks to expensive. Which then should be some easy money for any good stock picker.
Is the market already inefficient ?
This argument reasonable at first but is there any evidence that the market is less efficient ? Let’s look for instance at the DAX 30, the major German index. It is hard to come up with good numbers but I do think that maybe between 10-15 % of the DAX is somehow invested via index funds with a clear trend towards more index ownership.
So let’s look how the DAX constituents have performed so far this year (as of Nov. 2nd). The Dax itself ytd is down -2,8% This is the YTD performance of the constituents: