[ThrustVectoring]

Over a long timeframe, the investment with the lowest risk of underperforming against inflation is broad-market equity index funds. Bear markets and corrections happen, sure, but the nigh-inevitable performance during bull markets more than covers for that. Over something like 30 years, the only question is whether your investment will outperform inflation or massively outperform it.

Like, the 5th percentile worst result is definitely worse for stocks compared to bonds over a one-year timeframe. But, the advantage of a better compound annual growth rate means that as you add more and more time to your investment timeframe, worst-case results for stocks get better compared to bonds. IIRC, the crossover point is very roughly 20 years out - at this point, the risk of stock corrections has been completely absorbed by having superior expected returns.

[docker_up]

You're talking strictly US index funds. Have you taken a look at Japan? What if the characteristics of the US markets turn into something more like Japan? Your entire thesis would be wrong, and you could lose a lot of money.

[bilbo0s]

You're right about that, but Thrustvectoring is right too. The lowest risk investment that will make you the most over the long term, at least historically, has been index funds. Of course, environments change, and past performance is not a guarantee of future results. As you correctly imply.

I think most responsible advisors would not say, "Put everything here!" Or, "Put everything there!"

You need to diversify a bit, and that diversification should be informed by your own personal appetite for risk. If you have a low appetite for risk, TIPS are the way to go. Maybe some small percentage of your assets diversified across other asset classes.

Conversely, if you have a high appetite for risk, I believe a responsible advisor would still recommend some smaller percentage in TIPS, and then maybe the majority of your holdings diversified across other asset classes.

[fujiters]

This is just an argument for diversification. Hold the world at market cap and you'll only lose money if the whole world's markets crash and stay down for decades. And if that happens, I'm not sure bonds are going to keep you from hurting.

[Lavery]

None of what you're saying is wrong, but remember the context here when using the historical performance of markets to talk about these kinds of hard-and-fast rules. The period for which we have market data also spans: the period with the fastest growth in global population, including population growth in developed markets; the outbreak of extended peace between world powers; and roughly tracks human exploitation of fossil fuels.

Which is not to say that this is for sure coming to an end (hopefully not peace!), but it's impossible to know that there will be similar growth going forward. Population may level off (in advanced economies, this appears to have happened), and while we may well find new energy sources and technologies, it's not likely any will offer the massive productivity gains seen in the advent of fossil fuel and the the internet.

[ThrustVectoring]

If things are bad enough that the 30-year treasury outperforms global stocks at maturity, then the correct hedge is canned food, guns, and ammunition. The most pessimistic long-term outlooks cannot be mitigated by any sort of market mechanism because that level of pessimism implies a breakdown of the market itself.

[Lavery]

But what you're talking about isn't guaranteed. There's a lot of room between "stocks rip higher forever" and "societal collapse".

I'm not saying the right call is 100% t-bonds, but when you say things like "Over something like 30 years, the only question is whether your investment will outperform inflation or massively outperform it", you're making guarantees based on data from a narrow slice of history that is also the most economically favorable period just about ever.

Equities are the residual claim on assets, and their outperformance is predicated on growth. Economic growth comes from growing population and productivity. Neither of those is a given.

[ThrustVectoring]

There's no world in which economic growth is low enough that 30 year bonds win out over equities, yet high enough that the US can afford to pay their debts in full without inflating them away. Economic growth isn't a given, sure, but there basically isn't a plan that works for that pessimistic of market conditions. If there isn't enough economic activity to support retiring a large majority of your generational cohort, then unless you save extraordinarily large amounts of money you simply don't get to retire.

[IkmoIkmo]

This is really underappreciated. I'm a big fan of diversification, and it can be very important to lower your risk-appetite if you're relying on your investment income in a short-medium timeframe (e.g. if you're planning on retiring in 5 years, being all-in equity is just silly, or if you're saving for a downpayment on a home in a few years, stock investing isn't the primary instrument to use), but in the long-term (e.g. a 25 year old thinking about early retirement someday) it just doesn't make sense to take too little risk.

And in part it's precisely because of the worst case scenario happens where worldwide stocks don't outperform treasury bonds, you're likely living in a world where your money isn't legal tender anymore anyway, and any stock/bond investment decision you ever made basically irrelevant.

So if decisions regarding the extreme downside risk are irrelevant, you might as well optimize for the upside.

[ThrustVectoring]

Do note that there is a maximum amount of aggressiveness, beyond which you basically guarantee that you go broke while making trades with positive expected value. If you flip a coin that wins you twice as much as you lose, and you bet your entire bankroll, you'll eventually lose the coin flip and with it your entire savings.

For broad-market equity indexes, this point is at roughly 140% stocks / -40% cash. So it's not close to being an issue with current market expectations for a 100% equity portfolio, but generally speaking there is a level beyond which you cannot further optimize for upside at the expense of downside.

[yasp]

Tell that to the people that invested in the Nikkei in 1989.

[ThrustVectoring]

Global market-cap weighted equity investment has done fine since 1989. And anyhow, Japan's lost decade is more of a central bank policy failure than anything else, and one that is unlikely to be repeated.

The pre-Soviet Russian stock market is probably a better example.

[marvin]

How did the Russian stock market do? I'm curious and haven't heard this discussed before.

[ThrustVectoring]

It did about what you'd expect out of a national stock market - that is, until the Soviets seized the means of production, at which point you had literally nothing.