A reader called last week with an interesting question: Should he sell his Series I U.S. Savings Bonds, on which the yield reset to zero percent as of May 1?

My answer: probably not. There certainly are drawbacks to the current iteration of Series I bonds, but people who bought them before 2002, as this reader did, have a sweet deal that they should hold on to.

The Series I yield comes in two parts: a fixed rate, which is set every May 1 and Nov. 1 and stays the same for as long as you hold the bond, and a variable rate that changes with the Consumer Price Index. You add the two rates together to get the current yield.

When the government calculated the variable rate on May 1, though, it came out to -5.56 percent. The six-month period that was used — October through April — was a time of substantial deflation, largely because of falling energy prices. That -5.56 percent was enough to wipe out the fixed rate for all I bonds, although, fortunately, the rate can never go below zero.

So, what the reader is left with is a bond that will earn nothing between now and November. Over the long haul, though, it’s guaranteed to earn more than the rate of inflation. Bonds bought between May and November of 2000 will outperform inflation by 3.6 percent, for example; those bought between November 2001 and November 2002 will beat inflation by 2.0 percent. That’s a pretty valuable guarantee. Unless you think that we’re living through a repeat of the 1930s, when deflation continued for years, I’d hold on to those older I bonds.

If you bought I bonds more recently, however, you’re not getting such a great deal. New bonds issued since May 1 pay only 0.1 percent over the rate of inflation. Unless you think inflation will be a huge problem in the future, you probably can do better with other investments (although maybe not with Series EE Savings Bonds, which currently lock in a fixed rate of just 0.7 percent.)