1) That over 15 million users so far are using Ad Blocker in either Google Chrome, Firefox, Opera, or Safari.. These 4 represent over 70% of current browser usage. Once people start blocking ads for free (and speeding up browsing) this trend will continue and hurt advertising revenue.
2) Cable subscriptions and usage have been plummeting. Time Warner lost 306,000 TV subscribers in Q3.
3) Insiders have been selling shares since the high $40s, early $50's.
4) The loss of competing clients due to the merger until the next earnings release after it happens.
5) Mergers and acquisitions are very tough on people, and they will lose talent that isn't promoted internally to competing agencies.