The fund tracks the iBoxx 3-Year Target Duration TIPS Index and adjusts its holdings of Treasury Inflation-Protected Securities (TIPS) issued by the US Treasury so that modified duration stays at roughly 3 years. Unlike typical TIPS ETFs, whose duration drifts with market conditions, this fund's key differentiator is that it maintains its target duration at all times.

It suits conservative bond investors who want an inflation hedge but also want to limit the risk of bond price declines from rising interest rates by keeping duration short.

Launched in 2011 by Northern Trust (FlexShares), it is a passively managed (index-tracking) ETF.

The fund holds TIPS issued by the US Treasury and adjusts its weightings every month so that the portfolio's overall modified duration stays at about 3 years. This preserves the defining feature of TIPS, whose principal rises along with inflation, while limiting price sensitivity to interest rate changes to the short-to-intermediate part of the curve.

• A target duration strategy that keeps duration steady at about 3 years regardless of market moves
• A dual-objective design that pursues inflation protection and interest rate risk management at the same time

Assets under management (AUM) stand at $2.5B, and the expense ratio is 0.18% per year.

Compared with similar inflation-linked bond ETFs such as SCHP and TIP, its duration is fixed at a shorter level, so its price swings tend to be relatively smaller when interest rates rise. Liquidity is somewhat lower than that of the large TIPS ETFs, but because of its target duration strategy, monthly rebalancing delivers consistent interest rate sensitivity.

Inflation-linked bonds tend to hold up relatively well when inflation expectations rise and real yields fall. Because TDTT manages its duration to stay short, its prices tend to fall by a limited amount when interest rates rise, compared with conventional long-term bonds.

When inflation concerns come to the fore, inflows into inflation-linked bonds as a group tend to increase, and demand from conservative bond investors who prefer short duration remains steady. In an environment of high interest rate uncertainty, interest in short-term TIPS ETFs has been growing.

Its strength is that fixed short duration delivers inflation protection and interest rate risk control together, but its liquidity and AUM are smaller than those of the large TIPS ETFs.

SCHP and TIP, shown in the table, have longer durations, which means a stronger inflation hedge but also greater interest rate risk. STIP, like TDTT, concentrates on short-term TIPS and can be considered as a direct substitute. If you want a 5-year target duration within the same FlexShares lineup, there is TDTF, and if you want broader inflation protection beyond inflation-linked bonds, products with commodity exposure such as PDBC are also options.

Here are the points to review before investing in TDTT. Because the strategy pursues inflation protection and interest rate risk management at the same time, it is important to check the current inflation environment and the direction of interest rates in advance.

In periods of rising real interest rates, bond prices can come under downward pressure even with an inflation hedge in place. When prices are stable, its return advantage over conventional short-term Treasuries may narrow, so changes in the inflation environment deserve attention.

This bond ETF suits investors who want inflation protection and interest rate risk control together through short duration. If you want TIPS exposure with a longer duration, compare SCHP and TIP, and if you want the same short-term segment, compare STIP before choosing.