O’Malia acknowledged that the industry was dissatisfied with the draft rule, published in December. “Based on the comments received we are clear that we have to go back to the drawing board on that one,” he said.

The draft categorises a block trade as one larger than 95% of other transactions in the previous calendar year and at least five times the largest of the mean, median and mode of transaction sizes for the same category of swaps in the previous calendar year.

While the commissioner signalled that concerns over the 15 minute limit for reporting block transactions had been heard and noted by the CFTC, he indicated that solving the issue would likely be a result of resolving the rules surrounding swap execution facilities, rather than those pertaining solely to block trades.

“If we can get the SEF rules right, we can make block trades a rarity. Not eliminate them, just rarer. So the definition of what constitutes a block trade will still be important,” said O’Malia.