Which Long-Term Bond ETF Is the Better Buy: State Street's SPLB or Vanguard's VGLT?

VGLT (Vanguard Long-Term Treasury ETF) charges 0.03% (vs. SPLB’s 0.04%) but yields 4.7% trailing-12-month, while SPLB (long-term investment-grade corporate bonds) yields 5.5%. Over five years, SPLB shows better risk-adjusted outcomes with a shallower max drawdown (-34.5% vs. -41.0%) and higher growth of $1,000 to $854 (vs. $712 for VGLT). The key trade-off highlighted is credit risk (SPLB) versus interest-rate sensitivity (VGLT), with both funds experiencing painful drawdowns during the 2022–2024 rate-hiking cycle.

Analysis

This is not a stock-selection catalyst so much as a macro allocation signal: the market is still paying up for carry, but the real separation is whether investors want duration convexity or spread income. In the next 1-3 months, VGLT should be the cleaner expression if growth data softens or the market starts pricing earlier easing; long-duration Treasuries can re-rate much faster than credit when yields fall. SPLB’s higher yield is only attractive if spreads stay tame, and that assumption is vulnerable in any earnings disappointment or tightening financial conditions.

The second-order winner is the issuer with scale and liquidity: VGLT’s larger asset base likely keeps it the default institutional vehicle for rapid beta expression, especially in de-risking episodes. STT gets a small structural benefit from offering a credible income alternative, but this is not the kind of product comparison that moves the needle at the earnings level unless flows are unusually large. The bigger competitive dynamic is between Treasury exposure and bank-loan/high-yield substitutes; if investors decide credit risk is no longer worth the incremental carry, longer-duration government bond proxies can see a rotation at the margin.

Contrarian take: the current debate may be underestimating how much upside duration still has if inflation prints keep cooling, because long bonds can outperform on both price and correlation benefits versus equities. The flip side is that VGLT is the more crowded consensus hedge; if rates back up on sticky services inflation or a growth re-acceleration, the drawdown can be sharp and fast. For SPLB, the hidden risk is that investment-grade credit often looks deceptively defensive until spreads gap wider, at which point the extra yield is consumed quickly by mark-to-market losses.

Key Decisions for Investors

• If the next CPI/PCE prints and Treasury auction demand confirm easing pressure, buy VGLT outright or via a 1-3 month call spread; the trade is duration convexity, not carry, and should be sized for a fast move in yields.
• If your base case is slower growth but not a hard landing, prefer a VGLT/SPLB relative-value long VGLT short SPLB pair: Treasuries should outperform when spreads widen even modestly, with the thesis invalidated if IG spreads stay tight and yields drift higher.
• Do not force an options trade in SPLB unless you are explicitly betting on stable growth; the extra 80 bps of yield is not enough compensation if credit markets reprice, so treat SPLB as a carry vehicle, not a crisis hedge.
• Watch 10-year Treasury yields and IG spread moves as the key falsifiers: a sustained backup in yields or 15-20 bps of spread widening would argue for reducing VGLT exposure and rotating toward shorter duration or floating-rate alternatives.