NEW YORK — Stocks indexes were mostly lower on Monday, with telecommunication companies leading the way down. AT&T Inc. fell the most out of the 30 stocks that make up the Dow Jones industrial average. Its competitor, Verizon Wireless, is expected to announce Tuesday that it will start selling Apple Inc.’s iPhone, breaking AT&T’s long hold on iPhone customers.

AT&T’s stock dropped 1.8 percent to $28.34. Apple gained 1.8 percent to $342.45.