i purposely divide our portfolios between several brokers to diversify the risk of one of them going bust (yes i know they are insured) / being hacked / having my money stolen etc. i think it is a 0 cost way of removing a real non 0 risk from my life.
anyhow two that i use are ameritrade and scottrade. they announced they are merging, so i called the "private client" person at Ameritrade up to tell him i was moving the account to fidelity. 15 minutes later they called me back and offered me $4000 to stay. So i called Scottrade, and they offered me $4500. At the end of the day I had an offer from both of them for $5500. i have to stay with them for six months, but im 10k richer (before tax) it seems irrational behavior on their part, but if you have an account with them you may want to give them a call and see what they can do for you.