X0101 EFFECT 33 LIVE 2017-02-16 0001144204-17-009333 485APOS 0001469192 MAINSTAY FUNDS TRUST 333-160918 S000026784 MainStay Epoch U.S. Equity Yield Fund C000180191 Class B S000026784 MainStay Epoch U.S. Equity Yield Fund C000180192 Class R1 S000026784 MainStay Epoch U.S. Equity Yield Fund C000180193 Class R2 S000026784 MainStay Epoch U.S. Equity Yield Fund C000180194 Class R3 S000026784 MainStay Epoch U.S. Equity Yield Fund C000180195 Class R6