Research published by McKinsey & Company this morning lays out in black and white what many have long suspected – that equity analysts consistently overestimate the future earnings growth of the companies they cover.

The consultant found that over the past 25 years, average earnings-growth estimates of 10-12% for companies in the S&P 500 were almost 100% too high. Average actual growth over the period was closer to 6% (see attached chart).