For a couple of recent takeovers I've been involved in that have been challenged, I've received notification of "settlements" consisting of some trivial additional disclosures plus $500,000 payments to the plaintiff lawyers.
It's like paying ransom to the Somali pirates - sure you get your hostages back, but you just ensured that someone else is going to get hijacked.
I don't know what the solution is, but it sure makes me mad.