Data as of Sep 12, 2026. Both funds on the fields they both publish, from the same sources.
IWB vs MBB: how they differ
IWB and MBB hold 0% of their weight in the same names, and IWB returned more over the year.
iShares Russell 1000 ETF and iShares MBS ETF.
What they hold in common
By the books each fund has filed, IWB and MBB hold 0% of their money in the same securities at the same weight.
| Only in IWB | Only in MBB |
|---|---|
| NVIDIA CORPORATION 6.73% | Freddie Mac 1.07% |
| APPLE INC. 6.03% | Government National Mortgage Association 0.97% |
| MICROSOFT CORPORATION 4.00% | UMBS, TBA 0.85% |
| AMAZON.COM, INC. 3.33% | Government National Mortgage Association 0.69% |
| ALPHABET INC. 3.00% | UMBS, TBA 0.66% |
| BROADCOM INC. 2.54% | Government National Mortgage Association 0.56% |
| ALPHABET INC. 2.42% | Government National Mortgage Association 0.55% |
| MICRON TECHNOLOGY, INC. 1.88% | Government National Mortgage Association 0.54% |
Weight overlap is an ETFIQ calculation: for every security both funds hold, the smaller of the two weights, summed. Above 50%, holding both is close to holding one of them twice. Holdings dated Jun 30, 2026 and May 31, 2026.
| IWB iShares Russell 1000 ETF | MBB iShares MBS ETF | |
|---|---|---|
| Where it sits | Core index fund | Core index fund |
| Issuer | iShares | iShares |
| What it is | Russell 1000 | Mbs |
| Total return, 1 year | +16.7% | −0.1% |
| S&P 500 over the same days | +17.5% | +17.5% |
| Gap to the S&P 500 | −0.8 pts | −17.6 pts |
| Expense ratio | 0.15% | 0.04% |
| Holdings | 1024 | 11144 |
IWB in plain words
IWB is an index equity fund tracking the Russell 1000. Over the year to Sep 11, 2026 it returned +16.7% with distributions reinvested, against +17.5% for the S&P 500 and +23.0% for the Nasdaq-100. The prospectus expense ratio is 0.15% a year. By its holdings filed for Jun 30, 2026, 92% of the fund by weight is stocks the S&P 500 also holds, across 1024 positions, with the top ten at 33.5%.
MBB in plain words
MBB is a bond fund tracking the Mbs. Over the year to Sep 11, 2026 it returned −0.1% with distributions reinvested, against +17.5% for the S&P 500 and +23.0% for the Nasdaq-100. The prospectus expense ratio is 0.04% a year. It sat 3.3% below its high of Feb 27, 2026 on Sep 11, 2026.
Questions people ask
- Which returned more over the last year, IWB or MBB?
- In the year to Sep 12, 2026, with distributions reinvested, IWB returned +16.7% and MBB returned −0.1%, so IWB returned more. One year is one year; the longer windows are in the table.
- Which is cheaper, IWB or MBB?
- IWB charges 0.15% a year and MBB charges 0.04%, so MBB is cheaper. Fees come from each fund's prospectus.
Other comparisons
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Where these figures came from
ETFIQ links to the documents behind every figure. It is not affiliated with any issuer, and a link is not an endorsement.
Cite this page. ETFIQ, IWB against MBB, data as of Sep 12, 2026. https://etfiq.com/compare/any/IWB-MBB Free to use with attribution; the underlying files are at Open data.
A comparison is not a recommendation. Standards and sources