You really think companies investing billions in things like Facebook are just throwing money at whatever they fancy and hoping it all works out? Investment banks employ thousands of people who do nothing but sit in their office and calculate if a certain security's price is off by fractions of a percent. Virtually everything that bank does is based on that analysis. They are very well-paid and a good market researcher is worth 100x his weight in gold-pressed latinum. They do fuck up, often publicly as it turns out, but that does not make their science any less refined.