Meh. Whatever your opinions on P = NP, the efficient markets hypothesis is unfalsifiable. You can only falsify a joint hypothesis of efficiency plus some model of information flow into a market.
Knuth is a notable exception, although he has to my knowledge never really vigorously advocated P=NP but merely suggested the possibility that P=NP and that the algorithms to transform NP problems into P problems could be very, very complex but still in P. Seems unlikely, though.