There is a bit of a problem with the match between derivative securities markets and the primary markets. We have long ago instituted principles, essentially high margin requirements, to prevent certain instabilities in the stock market, and I think they're basically correct. The trouble is that there's a linkage, let's say, between something like the stock market and the index futures markets, and the fact that the margin requirements are very different, for example, played some role in the October '87 crash.