Apple’s (AAPL) “HomeKit” has been slow to gain traction in the home security market, but AT&T (T) and Comcast (CMCSA) are making inroads vs. incumbent ADT (ADT), says a Citigroup report. Apple launched HomeKit in 2014. So far, there are only 15 HomeKit-enabled accessories from five manufacturers posted on Apple’s site, though “many more” are expected in coming months, said Citigroup analyst Jason Bazinet in the report.