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Originally Posted by Biesterfield
How about just CAPM?
capm is just used to derive the cost of equity. so let's say we value aapl using capm to get our coe (i think this is a cool idea and would be fun for this thread to help op).
what are your underlying assumptions? what are you using as the rf (10y, 30y, why?)?
you'd need things like the beta and how/why you derived that beta. a decent and verifiable pricing strategy, etc. in addition we'd need to have some sort of consensus (and hopefully cogent) return for the peer market.
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In a market efficient world, expected return is proportional to risk.
but our market isn't efficient. if our market was efficient, trading would not be a profession. nor would active management. people would instead speculate on systemic risk solely using indexes because there would not be individual security risk.
second, the whole reason people create models is because exactly what you just said is very often not true. it's the reason that people take bets like CDS on JGBs or treasuries.
often times because of a variety of reasons (biases, bubbles, liquidity issues, systemic or cyclical problems) those spreads can widen. and as somebody mentioned before like was the case in the housing bubble, or the similar real estate based bubble in japan a few decades ago, or with the real estate crisis in florida in the early 1900s, or with tulips in 15th century europe.
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Its pretty easy to see that Apple is riskier than a money-market,
while this might be implicitly true. you should be able to prove this. why is a money market less risky than aapl? mathematically how would you model that?
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thus its expected return is higher.
like i said earlier. many times the price of an asset can become dislodged with its return. and this goes both ways. thats the whole point of having undervalued and overrvalued securities. (i'm not saying that AAPL is one way or the other, i'm only an advocate for the methodology behind finding that accurate price before making any assumption, especially if that assumption reflects your entire portfolio.)
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Note that this risk is measured as beta, which is only systematic risk.
beta is a measure of volatility, NOT, risk. beta is a component OF risk, but it certainly is not the only consideration.
risk is measured by volatility * the premium (which is given by the spread between the return for the market and the risk free rate, neither of which were discussed so far but both of which are important considerations)
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Since OP is only investing in one stock (horrible decision obv), he will encounter diversifiable risk as well, but that is beside the point.
agree that it's a horrible decision, which is why i suggested mitigating that diversifiable risk with an aggressive blended strategy. or, if he were to not, to make sure to very thoroughly value the two scenarios of cash and AAPL.