AGG vs IUSB

The Bloomberg U.S. Aggregate Bond Index is the standard measure of U.S. dollar investment-grade bonds with fixed rates. It covers Treasuries, government-related securities, corporate bonds, agency mortgage pass-throughs, commercial mortgage-backed securities and asset-backed securities, and it leaves out inflation-protected bonds, tax-exempt municipal bonds and high-yield corporate bonds.

AGG tracks the standard Bloomberg U.S. Aggregate Bond Index and held 13,486 lines in its holdings file on Nov 6, 2026.

IUSB tracks the Bloomberg U.S. Universal Index, which holds everything in the Aggregate and adds high-yield corporate bonds, emerging-market debt and other securities. It held 18,359 lines on Nov 6, 2026. The Universal index is a superset of the Aggregate, so most of the two portfolios is the same kind of bond; the extra layer is what separates them.

Holdings counts are not directly comparable: some are a count of bonds, others a count of lines in a holdings file, which can include cash and futures.

The largest bond line in AGG is 0.40% of the fund (Nov 6, 2026) and the largest in IUSB is 0.50% (Nov 6, 2026). The AGG top ten is all U.S. Treasury notes, while the IUSB top ten is not (see the table). The top ten total 3.93% of AGG and 3.84% of IUSB.

The two lists are dated differently on purpose, because each issuer publishes holdings on its own schedule: AGG Nov 6, 2026 (iShares holdings file); IUSB Nov 6, 2026 (iShares holdings file). AGG’s largest single line is a money market fund holding cash (2.63%), left out of the list above. IUSB’s list includes a mortgage security sold on a to-be-announced basis (TBA), which is a forward purchase of a pool of mortgages rather than a single named bond.

11,817 individual bonds appear in both funds, out of 13,484 distinct bonds in AGG and 16,434 in IUSB. Adding up the smaller of the two weights for every shared bond gives a portfolio overlap of 55.6%.

That is a floor, not a ceiling, for three reasons: the files are dated Nov 6, 2026 and Nov 6, 2026, so bonds that matured or were bought in between show as unshared; some weight carries no bond identifier (84% of AGG and 77% of IUSB is matched to an identifier), mostly mortgage securities and cash; and the funds may identify the same mortgage pools differently.

Shared bonds are ranked by the smaller of the two weights. AGG: Nov 6, 2026. IUSB: Nov 6, 2026. Weights are percent of each fund’s net assets.

Corporate bonds split three ways

Each issuer uses its own labels (AGG: Sector (iShares label), Nov 6, 2026; IUSB: Sector (iShares label), Nov 6, 2026). This page groups them into common categories: “Treasury and agency” adds Treasury, agency and government lines; corporate adds industrial, financial and utility bonds; “Other and cash” holds the remainder.

AGG: Maturity (iShares label), Nov 6, 2026. IUSB: Maturity (iShares label), Nov 6, 2026. Where an issuer reports narrower bands, they are added together to match the common bands shown.

80% of AGG and 81% of IUSB sits between one and ten years, and 10.0% of AGG and 9.5% of IUSB runs past 20 years. Average effective maturity is 8.16 years for AGG and 7.96 years for IUSB. Both funds are intermediate in profile, and the gaps between the bands are small.

Duration estimates how much a bond fund’s price moves when yields change. A duration of 5.73 years means a rise of one percentage point in yields would lower the price by about 5.73%, and a fall of one point would raise it by about the same. AGG reports effective duration of 5.73 years (Nov 6, 2026); IUSB reports effective duration of 5.54 years (Nov 6, 2026). That is a difference of 0.19 years, which is too small to matter.

Estimate: price change ≈ −duration × change in yield, applied to $10,000. It ignores interest income, convexity, spread changes and trading costs, so real results will differ. AGG reports convexity of 0.48 and an option-adjusted spread of 30.89 basis points (Nov 6, 2026); IUSB reports convexity of 0.45 and an option-adjusted spread of 53.92 basis points (Nov 6, 2026).

The 30-day SEC yield is the standard way to compare bond funds because every fund calculates it the same way, after expenses. AGG showed 4.98% and IUSB showed 5.21%, a gap of 0.23 points. Both figures are dated Nov 6, 2026. Yield to maturity is shown with its date where the issuer publishes it. Trailing 12-month yield is a record of what was paid, not a forecast: 4.12% for AGG and 4.33% for IUSB.

Monthly payouts per share, newest first

Third-party payout history (StockAnalysis, Nov 9, 2026), the 12 most recent payouts listed, which include two in December 2025 and none dated January 2026. Per-share amounts differ because the funds have different share prices (about $97 against $45), so compare yields, not dollars per share. Bond fund payouts change from month to month with the income the fund earns.

Average annual returns to September 30, 2026

Calendar-year returns

Net asset value (NAV) total returns, with distributions reinvested, from iShares fund page and holdings file (Nov 6, 2026) for AGG and iShares fund page and holdings file (Nov 6, 2026) for IUSB. Past performance does not guarantee future results. The funds launched in different years (AGG Sep 22, 2003, IUSB Jun 10, 2014), so since-inception figures (2.95% and 1.93%) cover different periods and are not compared here.

IUSB charges 0.03 percentage points more, which is $3 a year more on $10,000. Both funds are large ($139.20B and $50.47B), and large funds usually trade with tight spreads. Neither fund’s fee is likely to be the largest cost of owning it: the choice of how much to hold in bonds, and for how long, matters far more than a few hundredths of a percent.

Interest from bond funds is generally taxed as ordinary income rather than at the lower rates that apply to qualified dividends, and the monthly distributions of these funds are mostly interest. For that reason many investors hold taxable bond funds in tax-advantaged accounts, such as retirement accounts, when they have the choice. Some interest from U.S. Treasuries can be exempt from state income tax; how much of each fund’s income qualifies is reported by the issuer after year-end and varies by fund and year.

Canadian and other non-U.S. investors face their own rules, including currency conversion and withholding considerations, and should check them before buying a U.S.-listed fund.

Every figure on this page, with its source, date and evidence grade. Open the issuer documents before relying on any number.

Third-party sources

StockAnalysis, AGG · StockAnalysis, IUSB.

Methodology and limits

• Issuer figures are shown with their own dates. Where the two funds report on different dates the page says so and does not mix them silently.
• Sector and maturity overlap are this page’s sums of the smaller weight in each common category, and are approximate because issuers use different labels.
• Holdings overlap matches bonds by CUSIP or ISIN between the two holdings files named above; bonds without an identifier cannot be matched.
• Figures that were unavailable are marked as such, and nothing was filled from memory or from another fund.
• Rate-sensitivity figures are estimates from reported duration only.

AGG vs IUSB, which is better?

Neither is better in general, because they do different jobs. AGG holds the U.S. investment-grade bond market through the Bloomberg U.S. Aggregate index, while IUSB holds the U.S. bond market through the wider Bloomberg U.S. Universal index, which adds high-yield and other lower-rated debt to the Aggregate. The right one depends on the role bonds play in a portfolio, the investor’s tolerance for interest-rate and credit risk, and the account used.

AGG vs IUSB, what is the difference in fees?

AGG charges 0.03% and IUSB charges 0.06%, a difference of 0.03 percentage points, or $3 a year on $10,000.

AGG vs IUSB, which has the higher yield?

AGG showed a 30-day SEC yield of 4.98% on Nov 6, 2026 and IUSB showed 5.21% on Nov 6, 2026. The gap is 0.23 points, measured on the same date.

AGG vs IUSB, how much do they fall if rates rise?

By duration, about 5.73% for AGG and 5.54% for IUSB for each one-point rise in yields, before counting the interest each fund earns. This is an estimate, not a forecast.

AGG vs IUSB, do they hold the same bonds?

Partly. The files compared here show 11,817 bonds in both funds, a portfolio overlap of 56%. AGG holds 13,486 bonds and IUSB holds 18,359. The sector overlap on this page is about 91%.

IUSB vs AGG, does the order change the comparison?

No. IUSB vs AGG and AGG vs IUSB describe the same pair of funds, and every figure on this page applies either way. The order only decides which fund is listed first.

AGG vs IUSB, can I own both?

You can, but because the two funds hold nearly the same market, owning both adds little diversification beyond owning one.

AGG vs IUSB, are they suitable for Canadian investors?

Both are U.S.-listed and trade in U.S. dollars, so Canadians face currency conversion costs and should check how interest income is taxed in their account type before buying.

Pathways, not rankings or recommendations.