There are a lot of rules out there regarding how much to invest in stocks vs. bonds. Every single one of these rules was pooped out by some financial adviser with no quantitative reasoning.

One common one: The percentage of your investments that should be in stocks is equal to 100 minus your age.

Advice from Kiplinger: “If you’re investing for retirement, keep 90% or more in stocks until you’re within six years or so of retirement.”

I don’t like hard-and-fast percentages, so here’s the rule I’ve been using my whole life: When investing in anything, invest just enough to make you nervous. It can apply to your whole stock portfolio, individual assets, or the cash you stow under your mattress. If you’re going to put money anywhere, put enough in there to make yourself nervous. Otherwise you won’t bother to keep track of it.

These days, treasury bonds make me nervous because the government is flooding the market with supply to fund their expensive stimulus programs and bailouts.