At a place like Goldman Sachs, you don't need quants or predictors. You call up the CEO of a company you want to post record profits, and you tell them if they don't do absolutely desperate, self-destructive things (screwing employees and customers for immediate gains), you will crash their stock and destroy their entire company. That CEO then has a choice. Be the one who killed the company, or be the one who kept it running for a few more weeks and delivered a record quarter that made Goldman Sachs happy.

Once you have the assets and capacity to actively manipulate the price of any stock at will, the market is a VERY different animal and no longer need to be understood at all. You simply force its hand.