One of the perverse effects of increased indexing and ETF activity is that it will tend to “lock in” today’s relative valuations between securities. When money flows into an index fund or index-related ETF, the manager generally buys into the securities in an index in proportion to their current market capitalization (often to the capitalization of only their public float, which interestingly adds a layer of distortion, disfavoring companies with large insider, strategic, or state ownership).
Thus today’s high-multiple companies are likely to also be tomorrow’s, regardless of merit, with less capital in the hands of active managers to potentially correct any mispricings. Conversely with money pouring into market indices, stocks outside the indices may be cast adrift, no longer attached to the valuation grid but increasingly off of it. This should give long-term value investors a distinct advantage. The inherent irony of the efficient market theory is that the more people believe in it and correspondingly shun active management, the more inefficient the market is likely to become.