Finance theorists believed that markets were made efficient by the actions of arbitrageurs and other knowledgeable investors, so there was no contradiction in those theorists seeking to take these actions themselves. Nevertheless, that they did so shows that they did not construe market efficiency as an already-achieved fact. Rather, the achievement of efficiency was a process perhaps an endless process' in which they could themselves sometimes take part and from which they could profit.

Donald MacKenzie, An Engine, Not a Camera, loc. 1115