Sales by a portfolio insurer as prices fell were an "informationless," mechanical response to changing prices, so in an efficient market they should not affect stock prices, which should be determined by the tradeoff of risk and expected return discussed in chapter 2. That prices were governed by that tradeoff was the reasoning of Myron Scholes's Ph.D. thesis, but it was not peculiar to Scholes; it was a fundamental tenet of finance theory.

Donald MacKenzie, An Engine, Not a Camera, loc. 808