Treasury I Bonds are savings bonds and can be purchased directly from the U.S. Treasury using the website, treasurydirect.gov. I Bond principal is adjusted for inflation based on the consumer price index for urban areas (CPI-U), so if inflation is 1% annually, the principal increases by 1%. They are currently being issued with a 0% fixed yield, and what is being reported as a 4.6% yield. This is the 2.3% semi-annual adjustment for inflation expected through October 2011, based on the inflation measurement for the month of April 2011.
These are similar to Treasury Inflation Protected Securities (TIPS), with a 0% fixed rate. What is not reported is that if the economy should experience deflation, the holder would have a negative yield as yield on a 0% coupon is derived totally from principal appreciation. For perspective, the historic average for inflation over the past 10 years has been 1.93%. In buying the I Bond an investor must lock in the money at a maturity for three, five or 10 years, as these are the only periods offered. Believing the current low interest rates will persist for any of the noted periods seems a bit outlandish in our opinion. Further, assuming inflation would persist for long periods at levels beyond the noted 10 year average, it also seems risky as the Fed has tools to fight inflation with the target rate as low as it is currently.
We do not recommend buying 0% fixed rate inflation-protected bonds at this time.