Data as of Sep 13, 2026. Both funds on the fields they both publish, from the same sources.
IWC vs XBI: how they differ
IWC and XBI hold 0% of their weight in the same names, and XBI returned more over the year.
iShares Micro-Cap ETF and State Street(R) SPDR(R) S&P(R) Biotech ETF.
What they hold in common
By the books each fund has filed, IWC and XBI hold 0% of their money in the same securities at the same weight.
| Only in IWC | Only in XBI |
|---|---|
| CAREDX 0.61% | MODERNA INC 2.87% |
| SELLAS LIFE SCIENCES GROUP INC 0.60% | TWIST BIOSCIENCE CORP 1.81% |
| NURIX THERAPEUTICS 0.59% | HALOZYME THERAPEUTICS INC 1.47% |
| PENGUIN SOLUTIONS INC 0.58% | NATERA INC 1.46% |
| OUSTER 0.52% | KYMERA THERAPEUTICS INC 1.45% |
| VIRIDIAN THERAPEUTICS ORS 0.48% | TRAVERE THERAPEUTICS INC 1.40% |
| INTERFACE 0.47% | ROIVANT SCIENCES LTD 1.39% |
| MBX BIOSCIENCES 0.45% | ORUKA THERAPEUTICS INC 1.38% |
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 Sep 10, 2026.
| IWC iShares Micro-Cap ETF | XBI State Street(R) SPDR(R) S&P(R) Biotech ETF | |
|---|---|---|
| Where it sits | Core index fund | Core index fund |
| Issuer | iShares | State Street |
| What it is | Russell Microcap | SPDR S&P Biotech |
| Total return, 1 year | +31.3% | +64.0% |
| S&P 500 over the same days | +17.5% | +17.5% |
| Gap to the S&P 500 | +13.8 pts | +46.5 pts |
| Expense ratio | not published | 0.35% |
| Already in the S&P 500 | 91.9% | 8.5% |
| Holdings | 1252 | 154 |
IWC in plain words
IWC is an index equity fund tracking the Russell Microcap. Over the year to Sep 11, 2026 it returned +31.3% with distributions reinvested, against +17.5% for the S&P 500 and +23.0% for the Nasdaq-100. By its holdings filed for Sep 10, 2026, 92% of the fund by weight is stocks the S&P 500 also holds, across 1252 positions, with the top ten at 5.1%. It sat 5.0% below its high of Aug 14, 2026 on Sep 11, 2026.
XBI in plain words
XBI is an index equity fund tracking the SPDR S&P Biotech. Over the year to Sep 11, 2026 it returned +64.0% with distributions reinvested, against +17.5% for the S&P 500 and +23.0% for the Nasdaq-100. The prospectus expense ratio is 0.35% a year. By its holdings filed for Sep 10, 2026, 8% of the fund by weight is stocks the S&P 500 also holds, across 154 positions, with the top ten at 15.9%. It sat 9.6% below its high of Feb 8, 2021 on Sep 11, 2026.
Questions people ask
- Which returned more over the last year, IWC or XBI?
- In the year to Sep 13, 2026, with distributions reinvested, IWC returned +31.3% and XBI returned +64.0%, so XBI returned more. One year is one year; the longer windows are in the table.
- How much do IWC and XBI overlap with the S&P 500?
- By their latest filed holdings, 92% of IWC and 8% of XBI by weight is stocks the S&P 500 already holds. Between the two funds, 0% of their books are the same securities at the same weight.
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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, IWC against XBI, data as of Sep 13, 2026. https://etfiq.com/compare/any/iwc-vs-xbi Free to use with attribution; the underlying files are at Open data.
A comparison is not a recommendation. Standards and sources