HTC has officially announced the android marshmallow update for One M9 and One A9 unlocked smartphones in USA. This information has been officially confirmed by the HTC ‘Mo Versi’ (VP of product management) on his twitter page. This update will reach the unlocked A9 and M9 handsets from tomorrow in USA. Later they may also roll out this software globally. The one a9 handset will receive the android 6.0.1 update while the one m9 will update to android 6.0 (marshmallow). The users will receive the android marshmallow firmware update notification on their device. Once you received then follow the instructions provided on your screen. The user can manually check for the updates by settings > about phone > software update.

Full Specifications - HTC One A9 and One M9