The London Metal Exchange's unprecedented move earlier this month to cancel close to $4bn in nickel transactions shocked market participants far beyond London commodity trading. LME boss Matthew Chamberlain appeared on television for days afterward defending the move, while hedge fund boss Clifford Asness led a chorus of financial voices in slamming the exchange.

Mark Thompson is one of them. A veteran metals trader and hedge fund manager who is now an executive at mining development firm Tungsten West, Thompson says he has been collaborating with traders and fund managers to consider next steps, saying the LME's actions hurt its reputation and put the future of the exchange in question.