AK isn't a manufacturer. It stands for Avtomat Kalashnikova. It's more like a model name. It is/was manufactured in dozens of former Comm-Block countries and by even greater numbers of different manufacturers. It comes in multiple calibers, multiple configurations including sniper versions and bullpup versions. Hell, Saiga even makes a version chambered to use shotgun shells in 12, 20 and .410 gauges.
Just like the AR in AR-15 stands for ARmalite. But Colt, Armalite, Bushmaster, and etc, etc, all make AR-15s.
Cordially,
Eric
(Just a teensy bit of a real life gun nut firearms enthusiast.)