Investors have another opportunity to protect their portfolios against inflation, according to Ned Davis Research. Treasury Inflation Protected Securities, or TIPS, are the "world's safest long-term investment," chief global macro strategist Joseph Kalish wrote in a note Tuesday. The asset's principal rises with inflation, in contrast to regular Treasury bonds, which could lose value if the yield dips below the rate of inflation. Investors flocked to TIPS this year as inflation rose, but fled in August on hopes that the Federal Reserve was proving successful at reining in inflation. Now, there are signals that it could be a good time to buy for those who are risk averse, Kalish said. In essence, the breakeven inflation rate has likely come down by too much, he believes. Currently, implied inflation rates calculated between nominal and real yields on 5-year, 7-year 10-year and 30-year Treasurys show inflation being contained over the immediate and longer terms, he noted. "Inflation expectations have retreated from their peak levels three months ago, and are averaging around 2.5% for CPI inflation across multiple time horizons. We think there is a good chance inflation will be higher than that," Kalish wrote. While there are a wide range of outcomes, he thinks there is a "reasonably good chance of CPI inflation running 3.0% or more down the road." Right now, he believes TIPS are relatively undervalued compared to nominal Treasurys. To be sure, Ned Davis remains neutral on TIPS from a fixed-income portfolio perspective, but believes it makes sense for those worried about inflation. "A modest real return, along with inflation and principal protection – that sounds like a pretty good deal if you're risk averse," Kalish said. — CNBC's Michael Bloom contributed reporting.