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OK, bro, cool story. (#971046).
Also congrats, @Undisciplined, you and @byzantine resurrected the MONEY CLASS series

Markets are not efficient, but they are effective. They are effective at finding the current price. -post #971046
These are meaningless statements, but in elaborating how they are meaningless we can learn A LOT about finance, financial markets, theory, and economics. So let's go.
Eugene Fama (#875931), the father of/most influential name associated with the ideas the world has condensed into "efficient market hypothesis," starts his assessments with a very simple and extremely powerful observation that, if I had any influence, I would hammer into the epistemological being of every economist (or person, really): the joint-hypothesis problem. fr Wikipedia:

“Any attempts to test for market (in)efficiency must involve asset pricing models so that there are expected returns to compare to real returns.”

Bro, if you say a price is wrong you are saying two things, not one.
so, to even make the statement that something is overvalued or undervalued you’re implicitly testing two things. First, you’re “testing” for market efficiency; and second, you’re testing the asset pricing model you’re comparing against. (not particularly sophisticated since you’re just verbally saying so, but still).
This is how I’ve put it in print before ("The Bubble That Never Was: Finance's Definition Problem"):
In a theoretical sense it’s a banal question: if the price of an asset is trading much higher than what it’s actually worth, it’s a bubble; if not, then it isn’t.
But who says? It’s not like we can rock up to the Chicago trading pits or the New York Stock Exchange and just observe an “actual” value next to the price, and quickly calculate a bubble ratio. There’s nobody around to, credibly and reliably, tell us what its real value is. When somebody inevitably does say what an asset is really worth, why would their opinion, unbacked by money (or biased by talking their own book), be more accurate than the sum total of the market that actually trades the asset?”
What the joint-hypothesis problem teaches us is that in your very words of saying “the market is not efficient because asset x is mispriced” you are making two tests, and outcomes can falsify/undermine either market efficiency or your asset pricing model. (=indeterminate.)

Simply put: the market could be inefficient, or your model could be incorrect.

What you’re doing when you’re approaching the world like that is to “disregard market prices as ephemeral fluff; they’re as arbitrary as other fads and can thus occasionally go mad.”
The hubris there, once you dig down into it, is Hayek’s The Fatal Conceit, the lack of humility on the part of those who think they know better than the sum total of market participants (i.e., "prices").
Like I said in the comment: we don't know that the price is "way too high" -- that is, to invoke that wonderful The Big Short scene in Michael Burry's hedge fund, what "makes it a bubble."
Regardless, we can only establish bubble-ness in hindsight. (and barely even that...)
efficient, in the efficient-market hypothesis framework here means something like "the globally, best guess, of current/publically available information about the future." = point being: there's no model/idea/conviction/belief that provides an improved pricing compared to it.
Guesses can be wrong, of course. But that's beside the point.

“The kindest thing I can say about those confidently throwing around the b-word at everything they dislike or don’t understand is that their judgments are premature.”

That's today's little money lesson. Peace, /J
108 sats \ 11 replies \ @grayruby 20h
I have hard time squaring the efficient market hypothesis with the current market dynamic of prices being impacted greatly by passive flows. If you have large buyers at any price whose capital outweighs that of the sellers/shorters how can the market be efficient?
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I think any time someone says the market is or isn't efficient, I want to ask them how they define efficient. There are tons of underlying assumptions that I think need to be examined
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30 sats \ 6 replies \ @grayruby 18h
I am defining based on the market's ability to accurately price based on current information and expected future events.
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I think it's the concept of accuracy that I'd question here. How would you know if a price at any given moment is "accurate"?
I agree that markets are becoming more self referential, but if you factor that self referentiality into what you consider as relevant information then I'm not sure what it means to say that the market is not efficient
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You can't know for sure but a stock trading at 100 years worth of revenue probably isn't priced efficiently. Even if you believe that stock's revenue with 10x, you can't possibly know that for sure.
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What about bitcoin that has no revenue?
That's exactly what I asked in the referenced post.
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yep, this is a good/relevant/level-3 type objection.
Happy to accept that it distorts info/makes it noisier to understand. But it's well-established in the literature that it only takes a small portion of active traders/investors to structurally shift the market price to EMH eq.
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24 sats \ 0 replies \ @grayruby 18h
I think that's fair but there must be some point as passive continues to grow that it completely overwhelms the ability of active traders to reprice the market.
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What's your point here?
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just defining terms
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53 sats \ 4 replies \ @holonite 19h
I understood only 0% of what you said, but as far as what I understood and know I have 2 questions (please forgive me if you think I am a noob)
  1. If markets are so “effective,” then why do prices often swing way more than real-world news can explain (Shiller, 1981)?
  2. And if prices are always “right,” how come simple strategies like buying recent winners keep working (Jegadeesh & Titman, 1993)?
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To the first point, markets incorporate vastly more information than anyone is aware of. We don't know all of the relevant realized outcomes that investors are reacting too, but there's way more than just what's in the news.
To the second point, I would first want to know if the variance in that strategy is the same. If it's greater, then I'd submit risk aversion might be part of the answer. There are more factors going into prices than just expected value.
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Very good, excellent, high-level objections. Esp that Chiller critique I know him and Fama went back and forth over, but I cant remember who "won" and what were the touching points. Limits to arbitrage, for sure
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0 sats \ 1 reply \ @quark 19h
Markets are just dominated by AI machines that continuously move the price very effectively to whatever price their owners want according to their insider information from politicians and other influential sources.
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lol, whatever their owners want. Uh-hu.
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Markets are not slave to theories!
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explain? Say more?
"Theory," in the correct sense of the word (like "framework"), is a way for us to understand/make sense of the world.
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Sorry, I missed to detail it. I mean it for
They are effective at finding the current price.
I think if that's a theoretical assumption, it's bullshit. I'm not that good in economics but as investor, I've always believed that the current prices determined by the so called equilibrium are the ones most manipulated.
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"most" manipulated... as opposed to the other prices that aren't even prices (i.e., don't exist)...?
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They always exist in the minds of the investors/buyers. Saying they "don't exist'' is again theoretically correct. What I mean the determination of current prices isn't just the outcome of one thing. It has a lot of other factors too.
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OK, true. Relevance?
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