Threats to AWACS

Recently, there has been a large proliferation of AWACS-type aircraft, with the system now being flown by over 22 air forces worldwide. Since the aircraft are such a massive force multiplier, combined with the fact that they are a incredibly vulnerable assets, I am surprised that there isn’t a huge market for anti-AWACS weapons for the countries not fortunate enough for Airborne radar assets, just a question, are there weapons out there that pose any threat to AWACS forces?