Originally Posted by
BlackPeter
No, this has nothing to do with efficient market hypothesis. This has something to do with Chaos theory.
But referring to your last statement - for brokers and (paid) analysts this is absolutely correct. If they could beat the market sustainably and in a statistically meaningful way, than they would not need their income from broking or analysing companies and from selling their "advice".
For successful investors its a bit more difficult to say ... but then I think the answer is still yes. Sure, there is Warren Buffet and some other big names - and to be honest, to date I have never checked how far their success streaks are away from the standard deviation, but I just checked it today for you - according to some algorithm at Google:
That's not that much more than the average 8% the index does per year, isn't it? And of course, a skilled and prudent investor will sit with his (or her) returns in the upper part of the Gauss curve. They have to, otherwise nobody could make less to satisfy the average, and as we all know, there are less lucky (or less prudent investors) who make less return than the average, and some even lose money including their shirts ...
So, yes, good investors will sit somewhat above the average ... and not so good investors somewhat (or lots) below. However - nobody will be able to predict what their specific shares are going to do in the future, despite taking prudent and skillful picks. Remember how Warren bought airline shares before Covid started?