What happened in August and September 1998 was not simply that international markets fell in concert (that would have had little effect on LTCM), but that very particular phenomena, which at the level of economic "fundamentals" had seemed quite unrelated, suddenly started to move in close to lock-step: swap spreads, the precise shape of yield curves, the behavior of equity pairs such as Royal Dutch/Shell, and so on.

Donald MacKenzie, An Engine, Not a Camera, loc. 1088