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What Happens to Bonds in a Stock Market Crash?

A reader writes in, asking:

“I have one friend who is paying 1% to have her assets managed for her. When I looked at the portfolio the advisor had her in, it seemed riskier than one might like given that she hopes to retire one year from now. I encouraged her to ask him, ‘If the market were to crash tomorrow and drop by half, will that change my plan to retire?’

I want to give a simple example and wanted to check something with you first. Let’s say she has $1,000,000, half in stocks and half in bonds. So if the market were to drop by half, then she would wake up tomorrow having lost $250,000, right?

So my question is, when assessing risk tolerance, is it sensible to assume the bonds will hold steady?”

The “if the stock market fell by half and bonds stayed level” scenario is one that I use myself, as I think it provides a very rough but quick and useful metric of how reasonable a person’s overall allocation is.

So, yes, I definitely think it’s sensible to consider such a scenario.

However, I wouldn’t say that it’s a good idea to put oneself in a real-life situation where you’re 100% reliant on bonds not falling when stocks fall. Because they could. On the other hand, they could increase in value while the stock market falls, thereby offsetting the loss somewhat.

In short, what happens with the bond holdings depends on a) the immediate cause of the stock market decline and b) the type(s) of bonds in question.

For instance, it may be instructive to look at what happened with the last big market decline in late 2008. The chart below (made using the Morningstar website) plots four different mutual funds from 1/1/2008-12/31/2010.

Mutual Fund Chart

  • The blue line is Vanguard Total Stock Market Index Fund (VTSMX),
  • Green is Vanguard High-Yield Corporate Fund (VWEHX),
  • Yellow is Vanguard Intermediate-Term Investment-Grade Fund (VFICX), and
  • Orange is Vanguard Intermediate-Term Treasury Fund (VFITX).

The stock fund obviously falls by quite a bit in late 2008.

The high-yield corporate bond fund (green) falls right along with it, though not as much. This is more or less what you’d expect, as a situation in which businesses suddenly look more risky is a situation in which people might not want to hold bonds from the riskiest businesses (i.e., high-yield bonds).

The investment-grade corporate fund (yellow) also falls, though not as much as the high-yield fund. Essentially, you have the same thing going on with investment-grade corporate bonds as with high-yield bonds, but investment-grade bonds are from less risky companies, so people aren’t running from them as much as they are from the riskier choices.

The intermediate term treasury fund (orange) goes up over the period in question, as people “flee to safety” — pushing up prices for the safest bonds (and pushing their interest rates down).

So that’s how different types of bonds behaved in one particular stock market decline scenario. But other scenarios can have different results.

For instance, the following chart shows the same four mutual funds from 1/1/2000-12/31/2003. In the dot-com crash, all three bond funds did just fine — even the high-yield fund had only minor bumps. And that’s about what you’d expect given that most businesses weren’t particularly in danger of failing to pay their obligations.

Dot Com Crash Chart

Alternatively, one could imagine various scenarios in which the market decides not that “U.S. businesses look much riskier than they did a month ago,” but rather that “the United States looks much riskier than it did a month ago.” In such a scenario, it seems likely that the investors who choose to “flee to safety” would not flee to Treasury bonds — and some would even flee away from Treasury bonds. So we would see a case in which Treasury bonds would fall (to some extent) while stocks and corporate bonds fall as well.

So, to summarize, yes I think it’s often helpful to think about a scenario in which stocks fall by half and bonds go nowhere. But it’s also a good idea to think about and prepare for other scenarios. (And in general, diversification is the tool to prepare for such scenarios.)

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