Lumifer comments on Blind Spot: Malthusian Crunch - Less Wrong

4 Post author: bokov 18 October 2013 01:48PM

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Comment author: Lumifer 23 October 2013 06:47:48PM 1 point [-]

EMH doesn't mean that you cannot deliberately contrive to lose money.

Under EMH is pretty hard to deliberately and consistently lose money. It's very easy to get additional risk (e.g. by not diversifying), but I don't think EMH envisions assets with negative expected return.

Comment author: gwern 23 October 2013 10:52:29PM 3 points [-]

Mm, the way I remembered was that by not diversifying, you were taking on additional uncompensated risk; not diversifying wasn't completely neutral, expected-value wise. (Also, there's obvious ways to guarantee losing money: trade a lot. The fees will kill you.)

Comment author: Lumifer 24 October 2013 12:57:52AM 0 points [-]

Yep, that's what I said -- that you can easily get additional risk by not diversifying.

And the trading fees are outside of EMH -- there are certainly plenty of ways to reliably lose money in the real world, but not in the EMH world.

Comment author: gwern 24 October 2013 01:34:46AM 0 points [-]

Yep, that's what I said -- that you can easily get additional risk by not diversifying.

I said 'uncompensated' risk.

Comment author: Lumifer 24 October 2013 03:17:07AM 1 point [-]

EMH doesn't say anything about uncompensated risks.

To get to risk premium you need something like CAPM or APT which are a different kettle of fish.