This is not extremely difficult jobs (the expert analysts can earn bigger dollar who can correctly predict the company movement). Some analyst blindly do it for their client, some are more independent. Many of them do their analyst base on others (copy cat) and some do that after the company reports...
Nevertheless, some upgrade because the turn aound story basis and some downgrade because not much movement on the market... For instance, CSB downgrade TOL because the market tell them it was overbrought along with these uncertainty environment...
