In part that was because the costs of portfolio insurance in situations of high. [causal]
That mattered less than it might have, because after October 1987 the market for the type of portfolio insurance sold by LOR, its licensees, and its competitors dwindled rapidly. In part that was because the costs of portfolio insurance in situations of high volatility (forgone gains and risks of being "stopped out") became evident, but it may also have been because the managers of "respectable" institutions such as pension funds wished to avoid overt pursuit of a strategy that was "tainted" by its association with the crash.
Donald MacKenzie, An Engine, Not a Camera, loc. 889