I think it's fairly safe to assume that the house broker for a stock will always have more influence than one of the others, Also the other major influence is of course an analysts Extel ( rating ) thus the nbr1 rated analyst who also happened to work for the house broker will have the most influence. But don;t forget unless you have a mate who works for the brokers, how on eathe could you find out about the upgrade/downgrade early enough to be able to trade on it?