ackman on index funds

http://assets.pershingsquareholdings.com/2014/09/Pershing-Square-2015-Annual-Letter-PSH-January-26-2016.pdfbill ackman on index fund
The problem of asset flows without regard to valuation is compounded by the fact that the most popular indexes are market-cap weighted. This means that the larger the market cap of the company, the larger its representation in the index. In other words, as the stock price rises, its weighting in the index increases, and the index fund is required to buy more of the company. While value investors typically buy more as stock prices decline (assuming intrinsic value has also not declined), market-cap weighted index funds do the opposite. They are inherently momentum investors, forced to buy more as stock prices rise, magnifying the risk of overvaluation of the index components.