Brokers, as part of their job, tell their clients what to buy and sell and how much they should pay for something. Big brokerage houses like Goldman Sachs publish their thoughts to advertise to the world how smart they are. Goldman published that Twitter is a lousy investment only worth $30 or less per share. So when Twitter got a bid to sell their company for $54 per share, and Twitter wanted to say no, they were really dumb to hire Goldman as their transaction advisors since Goldman was already on the record as saying they're a bad investment.