I enjoyed both the perspective and the tone of the post. Up voted.
Two, probably not to deep thoughts.
First, years ago I had a discussion with some day traders and one was talking about the SPY EFT He mentioned that the fund owners actually did not invest in all 500 equities but only in the top performing ones (no idea what the criteria was on that). The argument was largely they could not make money running the fund if the invested in both the winning and losing stocks.
Second, and it relates to the first, one of the other things (different time) that was pointed out was “market” is a problematic terms. Each asset that is traded has a market and that is not the same as “the market”. I think this tends to be something of a problem area for people when the issue of EMH is in question. Many (most) do okay in thinking about a market in APPL (supply and demand, buyers/sellers, bids and offers) we all get that. But “the market” is a much more complicated (even chaotic) animal. At a high level most also get general portfolio theory but probably could not put a customized plan in place for their personal portfolio. What I suspect happens here, with regard to EMH, is a bit like the fallacy of composition error you get in logic. It’s not clear to me exactly how easy it really is to sum up the many demand and supply functions for each individual asset and then suggest any aggregate price or return to “the market”.
EMH (or at least most of the discussion here and everywhere else I’ve seen) doesn’t seem to make any distinction between the asset’s market and the general market (much less the global market).
Second, and it relates to the first, one of the other things (different time) that was pointed out was “market” is a problematic terms. Each asset that is traded has a market and that is not the same as “the market”. I think this tends to be something of a problem area for people when the issue of EMH is in question.
Yes! This is another really great point. I think Noah Smith described it by saying something like, ‘there is no EMH—there are an infinite number of EMHs all happening at the same time’. Which is another reason the theory is vague and unfalsifiable.
I find it helpful to think about each market in the narrowest possible terms. For example, the market for AAPL stock is likely to be less efficient than the S&P 500 market as a whole, although presumably not by much. The market for a thinly-traded stock languishing on the secondary board of the Tanzanian stock exchange is likely to be much less efficient than that. The market for a private company with no disclosure obligations is much less efficient again. By the time you get down to ‘the market for the time and labour of this one guy called Richard’, there are truckloads of inefficiencies and EMH doesn’t really apply.
I enjoyed both the perspective and the tone of the post. Up voted.
Two, probably not to deep thoughts.
First, years ago I had a discussion with some day traders and one was talking about the SPY EFT He mentioned that the fund owners actually did not invest in all 500 equities but only in the top performing ones (no idea what the criteria was on that). The argument was largely they could not make money running the fund if the invested in both the winning and losing stocks.
Second, and it relates to the first, one of the other things (different time) that was pointed out was “market” is a problematic terms. Each asset that is traded has a market and that is not the same as “the market”. I think this tends to be something of a problem area for people when the issue of EMH is in question. Many (most) do okay in thinking about a market in APPL (supply and demand, buyers/sellers, bids and offers) we all get that. But “the market” is a much more complicated (even chaotic) animal. At a high level most also get general portfolio theory but probably could not put a customized plan in place for their personal portfolio. What I suspect happens here, with regard to EMH, is a bit like the fallacy of composition error you get in logic. It’s not clear to me exactly how easy it really is to sum up the many demand and supply functions for each individual asset and then suggest any aggregate price or return to “the market”.
EMH (or at least most of the discussion here and everywhere else I’ve seen) doesn’t seem to make any distinction between the asset’s market and the general market (much less the global market).
Yes! This is another really great point. I think Noah Smith described it by saying something like, ‘there is no EMH—there are an infinite number of EMHs all happening at the same time’. Which is another reason the theory is vague and unfalsifiable.
I find it helpful to think about each market in the narrowest possible terms. For example, the market for AAPL stock is likely to be less efficient than the S&P 500 market as a whole, although presumably not by much. The market for a thinly-traded stock languishing on the secondary board of the Tanzanian stock exchange is likely to be much less efficient than that. The market for a private company with no disclosure obligations is much less efficient again. By the time you get down to ‘the market for the time and labour of this one guy called Richard’, there are truckloads of inefficiencies and EMH doesn’t really apply.