In cases of two types, however, the predictions of the two explanations differ. Type one is cases in which there is a range of similar spreads or implied volatilities in only some of which LTCM had positions. The superportfolio explanation would then predict greater increases in the spreads or implied volatilities in which LTCM had positions than in those in which it did not (assuming that, as was in general the case, LTCM held the less liquid instrument or was short volatility, in other words had sold the options in question). If the spreads or implied volatilities genuinely are similar, the flight-to-quality explanation would, in contrast, predict similar movements of them all.

Donald MacKenzie, An Engine, Not a Camera, loc. 1077