According to this RISK article Tradeweb was able to pick up as much as 80% of the interdealer volume in index credit default swaps (CDSs). Obviously, swap execution facilities have the ability to pick up a significant amount of business even though not mandated by the CFTC yet. As one London-based trader said: "The effect is that everybody has migrated to this platform." Let's see how this develops and let's not spell the end of SEFs just yet… Tom.