This is a long-term Treasury ETF that tracks the performance of long-maturity US Treasuries. Because it holds only bonds issued by the US Department of the Treasury, credit risk is virtually nonexistent, and its long duration makes it highly responsive to changes in interest rates.

It suits investors who want to prepare for a period of falling rates or add a defensive asset with low correlation to equities to their portfolio.

It is a passively managed (index-tracking) ETF run by State Street.

The fund tracks an index composed of long-maturity US Treasuries. Rather than holding every issue, it uses a sampling approach, selecting a subset with similar risk and return characteristics. Because it holds only Treasuries, credit risk is minimal, but its long duration makes it highly sensitive to interest rates.

• A fee that is low relative to the category average
• Monthly distributions that provide stable cash flow

Assets under management (AUM) stand at $11.6B, and the expense ratio is 0.03% per year.

Compared with VGLT in the same long-term Treasury category, it has a different fund manager, and it differs from TLT in its fee level.

As is typical of long-term Treasury ETFs, the price swings sharply with the direction of interest rates, tending to weaken when rates rise and strengthen when rates fall. Recently as well, volatility has continued as expectations for monetary policy shift.

When rate cut expectations grow, money tends to flow in on demand for duration bets, while inflows give way to outflows when concerns about rising rates intensify. Money also tends to gather during periods of market stress, when demand for safe-haven assets rises.

Its strengths are a low fee and exposure to Treasuries with no credit risk, while the main risk is interest rate sensitivity stemming from its long duration.

TLT and VGLT, shown in the table, are direct substitutes in the same long-term Treasury category. The former has an edge in liquidity and the options market, while the latter is a low-fee product from a different fund manager. TLH covers the intermediate-to-long segment and has a somewhat shorter duration, while EDV and ZROZ use a zero-coupon bond structure and tend to have even longer durations. If you also want short-term Treasury exposure, you can consider SHY, and for the intermediate segment, IEF.

Here are the points to review before investing in SPTL. Although long-term Treasury ETFs are classified as safe-haven assets, it is best to check interest rate sensitivity stemming from the long duration, the impact of inflation, and the currency exposure of Korea-based investors before buying.

Interest rate sensitivity stemming from the long duration is the main risk factor. When rates rise, even a safe-haven asset can see a large price decline, and in an inflationary environment real returns can weaken.

It is a suitable choice for betting on falling rates or as a defensive asset for an equity portfolio. If cost matters most, compare it with alternatives such as VGLT, and if liquidity and options matter most, with TLT.