One of the arguments given in favor of the creation of the Commodity Futures Trading Commission (CFTC) in 1974 was the need to extend regulation to previously unregulated commodities. Under the CFTC's predecessor, the USDA Commodity Exchange Authority, futures markets for such international commodities as coffee, cocoa, sugar, and the metals had been largely unregulated. The argument in favor of increased regulation for these markets was parity-all U.S. futures markets should be treated alike. In arguing against increased regulation, domestic exchanges trading futures contracts on international commodities stated that federal regulation would drive business to competitive markets overseas, where traders were unfettered by regulations which required filing reports on their positions and trading. In fact, a representative for three exchanges claimed that if any of the bills calling for the creation of the CFTC were passed, the three exchanges would go out of business in four or five years (Chapin, p. 472). More recently, the argument has been reversed. One of the reasons given for the rapid growth of U.S. futures markets compared to British markets is the greater investor protection in U.S. markets because of federal regulation (Hewson, p. 14). In addition, new legislation and/or regulatory bodies for futures markets are being considered in Canada, England, France, and Australia. The purpose of this paper is to consider the competitive effects of market regulation. Briefly, we will describe regulatory differences between U.S. and British futures markets and then, using intervention analysis, examine the level of activity on competing U.S. and British futures markets for cocoa, coffee, and sugar during the period 1970 to the present to see if important regulatory changes affect the volume of trading on these markets. Testimony provided to a Senate committee by the CFTC indicates that in the United States foreign traders make up a sizable proportion of all futures traders holding reportable positions in these commodities. The data revealed that about 30% of the long side and 45% of the short side of the total open interest in these commodities on 24 May 1983 was held by reportable foreign traders (Phillips). Commercial multinational firms are the predominant users of these futures markets. They are highly sophisticated traders who follow international prices and government policies closely and are experienced in dealing with foreign trade risks. As a result, it is assumed that they could shift their futures trading from one market to another if they wished to avoid regulation they considered too burdensome. It should also be noted that in addition to regulation, a number of other factors affect a trader's choice of futures markets, including exchange rate risk and foreign exchange controls, futures contract differences, taxation, and international and national commodity programs. This brief paper, however, does not allow us to consider these factors.