The iShares Core Composite Bond ETF (ASX: IAF) is one of the largest and most widely used fixed-income ETFs in Australia, giving investors broad exposure to the domestic Bond Market in a single trade. After years in which rising interest rates weighed on bond prices, the fixed-income landscape in 2026 is more nuanced, and IAF sits at the centre of the question of what comes next for Australian bonds.

In September 2026, with the Reserve Bank holding its cash rate at 4.35% and Inflation still above target, bond yields remain elevated. That means IAF offers a more meaningful running yield than it did during the ultra-low-rate era, but also carries interest-rate risk if yields move. This article explains how IAF works, why it is in focus, and the catalysts and risks ahead.

What is the IAF ETF?

IAF is a passive fixed-income ETF issued by BlackRock under its iShares brand. It aims to provide the performance of the Bloomberg AusBond Composite 0+ Year Index, before fees and expenses — a broad benchmark of the Australian bond market. The index includes investment-grade, Australian-dollar-denominated fixed-income securities issued by the Australian Treasury, state (semi-government) entities, supranational and sovereign issuers, and corporations. The fund charges a management fee of 0.10% per annum and pays distributions quarterly. It launched in 2012.

The portfolio is diversified across hundreds of bonds — independent data has cited around 744 holdings — spanning government, semi-government, supranational and corporate issuers, all rated Investment grade. The largest exposure is to Australian government and state bonds, with a meaningful minority in high-grade corporate and international issuers. Because it spans the full Maturity spectrum, IAF carries meaningful duration, meaning its Capital value rises when yields fall and falls when yields rise. It is designed as a core defensive building block within a diversified portfolio.

What is driving interest now?

The key driver is the interest-rate environment. The RBA held its cash rate at 4.35% at its August 2026 meeting, and ahead of the 29 September decision the market has priced a hold or possible hike rather than cuts. Because bond prices move inversely to yields, the path of interest rates directly shapes IAF’s returns: if yields fall, IAF’s capital value tends to rise; if yields climb further, its capital value can decline, offsetting some of the income.

A second driver is the renewed appeal of income. With yields elevated, IAF offers a running yield of around 3% — far more attractive than during the near-zero-rate years — which has drawn investors back to fixed income as a source of defensive income and portfolio diversification. Fixed-income ETFs have seen strong inflows in 2026 as investors seek to lock in higher yields and add ballast to portfolios dominated by equities.

Portfolio and holdings

IAF’s performance is driven by two things: the income from its bond holdings and the effect of changing yields on their capital value. The portfolio is dominated by Australian government and semi-government bonds, which make up the bulk of the fund, with corporate and supranational issuers adding Diversification and a modest yield pickup. All holdings are investment grade, rated between AAA and BBB.

The most important characteristic for investors to understand is duration — the sensitivity of the fund’s value to interest-rate changes. Because IAF holds bonds across the full maturity spectrum, it has moderate-to-meaningful duration, so movements in market yields can drive noticeable swings in its unit price. This is what distinguishes IAF from a cash ETF: it offers higher potential returns and diversification benefits, but with genuine interest-rate risk.

Catalysts to watch

Several factors could influence IAF in the coming months: the RBA’s 29 September rate decision and the future path of the cash rate; the trajectory of Australian inflation, which shapes monetary policy; movements in longer-dated bond yields; global bond-market trends and offshore yields; and investor Demand for fixed income as a defensive allocation.

Risks

IAF’s main risk is interest-rate (duration) risk: if yields rise, the fund’s capital value can fall, potentially offsetting its income. Credit risk is relatively low given the investment-grade portfolio, but not absent, particularly for the corporate holdings. Inflation risk can erode the real value of fixed income if inflation stays high. Market Risk and index-tracking risk apply. Unlike a cash ETF, IAF’s unit price genuinely fluctuates, so it is not a capital-stable holding, even though it is more defensive than equities.

Outlook

IAF remains a core, low-cost way for Australians to hold a diversified basket of domestic investment-grade bonds, and the higher-yield environment has made it more appealing as a source of income and diversification. Its near-term returns hinge on the direction of interest rates: elevated yields support income, but the capital outcome depends on whether yields fall or rise from here. Investors may be watching the September RBA decision, inflation data and bond yields for direction. The outlook may depend on whether Australian rates have peaked or move higher, which would shape the balance between income and capital returns.