iShares U.S. Aggregate Bond Index Fund

BlackRock Funds III · 1 share class

U.S. equity index fund
One fund, 1 share class:WFBIX
$3.27B NAV
1 positions · as of 2026-06-30 · filed 2026-08-25

Fund classification

Classified from what the fund holds · as of 2026 Q2

iShares U.S. Aggregate Bond Index Fund is a U.S. equity index fund that tracks the Bloomberg U.S. Aggregate Bond Index.

Asset class
Equity
Region
United States
Management
Index (passive)
Fund type
Open-end fund
Features
Master-feeder

Fund profile

As filed in the prospectus · 2026 Q2

The investment objective of iShares U.S. Aggregate Bond Index Fund (the Fund ), a series of BlackRock Funds III (the Trust), is to seek to provide investment results that correspond to the total return performance of fixed-income securities in the aggregate, as represented by the Bloomberg U.S. Aggregate Bond Index (the Bloomberg U.S. Aggregate Index or the Underlying Index ).

Strategy · summarised

The fund seeks to match the total return of the Bloomberg U.S. Aggregate Bond Index by investing in a representative sample of the approximately 14,006 investment-grade fixed-income securities in the index, including government bonds, corporate bonds, mortgage-backed securities, and asset-backed securities, with securities selected according to their relative weight in the index and characteristics such as credit quality, sector, and maturity. Because the fund invests in a representative sample rather than all index constituents, its returns may diverge from the index. The fund is structured as a feeder that invests all assets in a master portfolio.

Expenses
0.05% 0.35%across 4 share classes
Share classExpense ratio
WFBIX0.05%
C0000991660.35%
C0000991670.10%
C0002019530.35%

Portfolio turnover 93.00% · as of 2026 Q2

Allocation

Asset groups · long / short shown separately, never netted · 2026 Q2

100.25%
of net assets
Stocks100.25%

Latest quarter

What changed since the fund's previous filing

2026Q2 vs 2026Q1

New and exited totals aren’t verifiable for this fund.

Return profile

Total return as filed — price change plus distributions reinvested · trailing figures to Apr 2026

1-year
+4.03%
3-year
+10.69%
5-year
+0.93%
Volatility
3.56%
Worst 3-yr fall
-6.11%
Cumulative return· Jul 2023 – Apr 2026

May 2026 and Jun 2026 have been filed since the trailing figures were struck, so they are not in the table above or the curve — every figure here shares one cut-off, which is what makes them comparable with other funds.

This fund changed legal form during the period shown. The history above is continuous — it spans both eras, and the change is not a gap in reporting.

Holdings

By % of NAV · equity positions carry filed share counts · every resolvable issuer links to its company page

Issuer%NAVValue
MASTER INVESTMENT PORTFOLIO100.25%$3.28B
Showing 1 of 1

Reported price is the fund's own reported value divided by its own reported shares at 2026-06-30 — not a live quote, and not what the fund paid.

Top 10 positions are 100.25% of net assets, top 25 100.25%, across 1 issuers.

See more of this fund's book

More positions with filed share counts, and the quarter-over-quarter change list rather than the largest few — free with an account, no card required.

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