CBS just announced that it will not order a fourth season of summer series Under The Dome.
The show, which is generally credited with making the summer TV season a potential ratings boom (and with it, advertising dollars), debuted in June of 2013 with nearly 18 million viewers (Live+7), outdoing all but one of the fall debuts in 2012. But with various plot twists over three seasons it shed viewers pretty quickly. It proved a strong performer for streaming services via Amazon, and will continue to be available there.
It is almost certain that CBS will renew Zoo, and it is believed that with Under The Dome out of the way, Extant has a stronger chance at renewal as well.