this post was submitted on 18 Oct 2026
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[–] UnderpantsWeevil@lemmy.world -1 points 17 hours ago (4 children)

DJIA crested a new high September 3rd 1929 before stumbling 3% the next week.

And over a century later, what has become of it?

If someone bought $100 of stock in 1929, how much would it be worth today?

[–] jj4211@lemmy.world 2 points 16 hours ago (3 children)
[–] UnderpantsWeevil@lemmy.world 1 points 16 hours ago* (last edited 16 hours ago) (2 children)

$100 of the entire DJIA on September 3, 1929 adjusted annually: $13,633

If you'd invested in January of 1929: $16,913

If you'd invested in January of 1920: $72,275

January of 1930: $31,708

It's never gone to $0

[–] jj4211@lemmy.world 1 points 1 hour ago (1 children)

This has strayed quite a bit from the assertion that there can't be enduring problems in the current crop of AI investment because it was at a high a while back.

But to continue, if you invested in the makeup of the DJIA in 1929 and left it in those companies, you would not be having a particularly good time.

If you kept refreshing the investment in the companies deemed to be the 'good' ones over time, then yes, your investment fared well, but that says nothing about the enduring value of the companies that made up the index in 1929. This is the current topic. It's also wild to be this dismissive of the Great Depression as nothing to worry about because, eventually, we decided on a new set of lines that could go up.

So "line goes up" by definition is not really an endorsement that all companies lines go up, we shift the criteria over time to make sure that we measure whatever works in that moment.

[–] UnderpantsWeevil@lemmy.world 1 points 2 minutes ago

if you invested in the makeup of the DJIA in 1929 and left it in those companies

Then you would no longer be investing in the DJIA as new companies were added.

But if you rebalanced periodically, you'd get the listed results.

So “line goes up” by definition is not really an endorsement that all companies lines go up

Diversification is one of the first lessons of practical investment. And blue chip indexes help simplify this process

If you switched from the DJIA to the S&P 500 or the NASDAQ, as these indexes emerged, you'd outperform the DJIA as it stood. I use the DJIA because it existed in 1929 while the others did not.