If you want an example of how someone can get carried away by what seem to be high interest rates, you don’t need to look at huge financial failures like Silicon Valley Bank, R.I.P.

Instead, you can look at me.

After watching my cash reserves earn almost no interest for years, I got so carried away last May when yields on one-year Treasury bills hit 2% that I bought a batch of one-year bills at the Treasury’s May 19 debt auction.

Oops. The Federal Reserve kept pushing rates higher and higher. And higher. Far more quickly than I’d expected, despite my 50-plus years of covering financial markets.

As things turn out, I’d have made considerably more interest income—about 50% more, according to money market fund maven Pete Crane of Crane Data—had I left the T-bill purchase money in my Vanguard Federal Money Market Fund account. (I’m using Vanguard in this article because that’s where much of my wife’s and my money is invested.)

Let me take you through the numbers, which I’ve rounded a bit to keep things relatively simple.

If you’d taken part in the Treasury’s debt auction last May 19, as I did, you’d have paid $9,788 for a T-bill that the Treasury will redeem for $10,000 this coming May 18.

Do the arithmetic by dividing $10,000 by the purchase price, and you see that my yield on that one-year T-bill was 2.17%.

At the time, Vanguard’s Federal money fund was yielding less than 1%, so earning 2%-plus was very attractive. However, the yield on the money fund began rising rapidly as the Fed kept jacking up rates. When last I looked, the seven-day yield on the fund was 4.72%. However, the T-bill’s yield to maturity stayed at 2.17% because T-bills are a so-called “fixed income” investment.

At my request, Pete Crane estimated what he thinks the Vanguard money fund will have yielded for the year that ends this coming May 18. His estimate: 3.12%. A spokesman for Vanguard, who did his estimate a bit differently, came up with a similar number: 3.26%.

Either way, it’s about 50% more than I’ll have earned on my T-bills.

Oh, well.

In my own defense, I bought one-year T-bills rather than longer-dated securities like 10-year Treasury notes because I figured that if I restricted myself to buying one-year bills, I’d be annoyed but not seriously damaged if interest rates rose rapidly. Which turned out to be the case.

If I’d bought 10-year notes, on the other hand, I’d have incurred serious risk because even though the Treasury will pay off the notes when they come due in 2032, their current market value would be considerably less than what I would have paid.