For all of the outrage kicked up by Michael Lewis’s depiction of fundamentally rigged securities exchanges in his book “Flash Boys,” there’s a giant obstacle standing in the way of punishing high-frequency traders or the exchanges that facilitate them: the blessing of federal regulators. As Dealbook’s Peter Henning wrote in his White Collar Crime Watch column on why high-frequency trading is unlikely to result in criminal charges, securities exchanges openly sell access to high-speed data feeds and to physical proximity that increases trading speed by milliseconds. Exchanges are, in the words of Andrew Ross Sorkin, “the real black hats” of high-frequency trading, since they unabashedly profit from differentiating access to trading information.