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Comment by briHass | Hacker News Reader

This is basically a restating of William Sharpe's famous 1991 paper that basically started the whole discussion.

"Properly measured, the average actively managed dollar must underperform the average passively managed dollar, net of costs. Empirical analyses that appear to refute this principle are guilty of improper measurement."

When someone picks active management over passive, they are really betting that they can beat, and hence are not, average. It's difficult for people to swallow their hubris, even when simple arithmetic shows them that they are (collectively) wrong.

http://www.cfapubs.org/doi/pdf/10.2469/faj.v47.n1.7

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when someone picks active management over passive, they're betting THEIR MANAGER can beat the average. people invested in buffett's stock picking skill; how are they doing?

What misses from the above analogy, is that if all of the "passive" half have a different random subset, then about half will by definition do "above average", and the other will do "below average". While in the "active group", less than half will do "above average" because they pay part of their gain to fund managers.

So if you want to beat the market, your chances are still better in the passive group...

Now, this doesn't take into account getting away with insider trading, of course. If you can get away with insider trading, then you can beat the market just fine.

> Now, this doesn't take into account getting away with insider trading, of course.

More importantly, it also doesn't take into account that there are investment opportunities that are not as directly (i.e., without intermediary layers which extract some of the returns) available to passive investors, so that the passive/act groups aren't splitting the same universe of alternatives. (E.g., passively investing in any given index fund is on average better than actively investing restricted to stocks in that index, and you can probably even extend that to passively investing in index funds in generally being better than actively investing in investments that directly held by any combination of index funds, but not every investment vehicle in the market is directly held by index funds.)

> half will by definition do "above average", and the other will do "below average"

Is this really true? I think it's only true if you replace average with median (e.g. in [1,2,3,10] only 10 is above the average).

A very good point! I would say that it depends on what the distribution looks like, I wrote:

> [I]f all of the "passive" half have a different random subset, then about half will by definition do "above average", and the other will do "below average". While in the "active group", less than half will do "above average" because they pay part of their gain to fund managers.

So, if all the passive investors have pick a random "large enough" subset of stocks, one would expect the distribution to approach the normal distribution, with roughly half to either side of the arithmetic mean.

Similarly, as you point out, on the "active" side, one might see more outliers - and perhaps the selection isn't really uniformly random.

So, it would probably be a stretch to claim that half will be above average "by definition", even if one includes the expected distribution, while note perhaps entirely wrong.

"Average" can refer to the median, or any of the various means. Its often informally used to mean the arithmetic mean (but also often the median), but it doesn't explicitly mean either of those.

Above average. Of course those people all made an above average choice in active management.

It's somewhat ironic that Buffett is using this analogy, as he made huge profits by being an active investor. You just need to be smarter than the average active investor, which in reality isn't very difficult. The best strategy seems to be to use value investing, which is how Buffett made his fortune. Buy undervalued stocks, then keep hold of them for the long-term (or at least, until they become overvalued, then sell some).

Isn't Buffett's case a bit different? He typically buys businesses outright, rather than making investments on the open market, so no passive investor (besides one in Berkshire Hathaway) could get those returns.

Also, as I understand it, Berkshire gets to implement management changes (if it deems them necessary) as it wishes, since it owns whole companies, and so the improvements they see could also come from better management of a business rather than picking better businesses. So arguments about average or above average stock picking ability seem less relevant here. (It could well be that Buffett has average management-picking ability, but is one of a relatively small number of market participants who both can and do exercise it, thereby getting an outsize result.)

Buffett also benefits from having Charlie Munger at his side. Buffet gets most of the credit but Munger is also a world class investor. It's like if Steve Jobs and Bill Gates had worked together.

He buys them outright now, but not when he was amassing his fortune.

Also, I believe he has bought a number of privately held business, which are almost always waaaaay cheaper (on a P/E basis for example) than publicly traded companies.

Right, you just buy low, and sell high. It's so simple, I don't know why everyone doesn't do it. In reality, there's nothing statistically inconsistent with a 5 sigma outlier like Buffett.

I'm not sure what your point is. Yes, it is as simple as buy low, and Buffett is saying the same thing. The main point is that most people aren't smart or confident enough to be able to [a] determine which stocks are undervalued and [b] buck the herd instinct.

That may be true that the "average" actively dollar will underperform but it should be easy (or at least possible) to identify the "above average" actively managed dollar.

It's actually quite difficult to identify above average.

ISTR a study a few years ago that said the only way you can know for certain that a fund manager is above average is on something like 30+ years of data. There's too much random variation.

I think it was the same article that said the baseball season would need to be several hundred games before you could definitively choose the best team in a given season.

Stepping back even further, a lot happens over 30 years. Wars, social change, major political movements, tectonic shifts in technology, etc.

Perfect example: Buffett has always touted value as a great investment strategy, but he completely missed the cocktail of global trade, speed, and scale that have driven Amazon, Google, Uber, Netflix, Apple, etc. to grow revenue and profits so rapidly.

Looking back, I think this shift into a world where it's possible for a company to go from zero to hundreds of millions/yr in net revenue over a span of 4-5 years (Uber) is really going to be seen as some kind of historical turning point in business, on par with the invention of the printing press, or electricity. Companies used to take a century to accomplish growth that's now possible in less than a decade.

Which is all to say, over a long enough timespan, you're talking about a pretty deep and complex philosophical question, what it means to be a "good investor" in the face of so much change, risk, etc. To be honest, I'm not sure it's something that's knowable at all.

I think it's actually supposed to be quite difficult to see who is above average. At least in "A Random Walk Down Wall Street", they cite some statistics about how only 20% (?) of managers beat the market over a period of time, but it isn't the same people who do it over different periods of time.

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