I am *shocked* that a physicist who claims to have a theory of everything for finance has fundamental misconceptions about how basic things like “stock indices” work.
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It seems what that paper is actually saying is that the S&P500 suffers from survivorship bias if used as a proxy for a generic diversified investment in US stocks, which I think is true, given it will not have the same distribution as a basket of all tradable US stocks
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Maybe
@ole_b_peters or@alex_adamou will care to explain what did they mean when they wrote that the S&P 500 suffers from survivorship bias.1 reply 0 retweets 0 likes -
Replying to @edwin_teejay @FPyLPython and
Isn't it clear in the quote? It is, by definition, an index of 500 successful companies, from which constituents are removed when they cease to be successful. So it's a basket of winners (survivors). Happy to be corrected factually by a market expert if wrong.
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Replying to @alex_adamou @edwin_teejay and
The historical performance of the index includes the performance all of the companies that were removed hence there is no survivorship bias in the index. This is a very simple concept and it is incredible that you don’t seem to understand it.
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Replying to @macrocephalopod @alex_adamou and
Like, you either don’t understand how the index performance is calculated or you don’t understand what “survivorship bias” means and either of those is pretty amazing if you are writing papers claiming to revolutionise finance.
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Replying to @breakingthemark @alex_adamou and
Now include the transaction costs from daily rebalancing to equal-weight and see what that does to the returns of the equal-weight portfolio!
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Replying to @macrocephalopod @breakingthemark and
Equal weight portfolios appear to perform cap-weighted partly because they have a loading on short-term reversion (buy losers, seller winners) which provides liquidity and is rewarded for that, but it doesn’t survive transaction costs (maybe 15 years ago but not now)
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Replying to @macrocephalopod @alex_adamou and
Wrong comparison. Why does the "market" clearly outperform the same exact securities left to evolve their weights on their, own never rebalanced, from 80 years ago? There are fewer transaction costs here, and it does worse.
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Sorry what is the “market” here? Is it different from the market (ie all stocks in proportion to their market cap)?
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Replying to @macrocephalopod @alex_adamou and
Matt Hollerbach Retweeted Matt Hollerbach
When a stock falls out of the index and another comes back in, the wealth from the one that falls out doesn't just transfer to the newly added stock because their market caps don't match. More wealth must be pulled out of other stocks.https://twitter.com/breakingthemark/status/1282880180990681091?s=20 …
Matt Hollerbach added,
Matt Hollerbach @breakingthemarkSome people have agreed with the principles of rebalancing in this post, but said that the S&P 500 is cap weighted, therefore it doesn’t rebalance in that same way as the Dow. I don’t think that’s true and we are about to see a reason why. https://breakingthemarket.com/why-market-index-investing-works/ …Show this thread1 reply 0 retweets 0 likes -
Replying to @breakingthemark @macrocephalopod and
If you don't pull wealth from other stocks and just transfer the wealth from one stock to the next, the index performs far worse than when wealth is rebalanced from the other stocks into the new one.
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