Data as of Sep 13, 2026. Both funds on the fields they both publish, from the same sources.
MDY vs XBI: how they differ
MDY and XBI hold 4% of their weight in the same names, and XBI returned more over the year.
SPDR S&P MidCap 400 ETF Trust and State Street(R) SPDR(R) S&P(R) Biotech ETF.
What they hold in common
By the books each fund has filed, MDY and XBI hold 4% of their money in the same securities at the same weight.
| Holding | MDY | XBI |
|---|---|---|
| United Therapeutics Corporation | 0.61% | 0.89% |
| Roivant Sciences Ltd. | 0.52% | 1.39% |
| Neurocrine Biosciences Inc. | 0.45% | 0.94% |
| Exelixis Inc. | 0.41% | 1.05% |
| Halozyme Therapeutics Inc. | 0.36% | 1.47% |
| BioMarin Pharmaceutical Inc. | 0.36% | 1.13% |
| Arrowhead Pharmaceuticals Inc. | 0.33% | 1.13% |
| Cytokinetics Incorporated | 0.28% | 1.06% |
| Krystal Biotech Inc. | 0.26% | 1.07% |
| Only in MDY | Only in XBI |
|---|---|
| Twilio Inc. Class A 1.00% | MODERNA INC 2.87% |
| Illumina Inc. 0.86% | TWIST BIOSCIENCE CORP 1.81% |
| TechnipFMC plc 0.86% | NATERA INC 1.46% |
| Everpure Inc. Class A 0.84% | KYMERA THERAPEUTICS INC 1.45% |
| Okta Inc. Class A 0.81% | TRAVERE THERAPEUTICS INC 1.40% |
| U.S. Dollar 0.80% | ORUKA THERAPEUTICS INC 1.38% |
| ATI Inc 0.77% | REVOLUTION MEDICINES INC 1.36% |
| nVent Electric plc 0.71% | PRAXIS PRECISION MEDICINES I 1.36% |
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.
| MDY SPDR S&P MidCap 400 ETF Trust | XBI State Street(R) SPDR(R) S&P(R) Biotech ETF | |
|---|---|---|
| Where it sits | Core index fund | Core index fund |
| Issuer | State Street | State Street |
| What it is | S&P MidCap 400 | SPDR S&P Biotech |
| Total return, 1 year | +13.0% | +64.0% |
| S&P 500 over the same days | +17.5% | +17.5% |
| Gap to the S&P 500 | −4.5 pts | +46.5 pts |
| Expense ratio | 0.23% | 0.35% |
| Already in the S&P 500 | 0.0% | 8.5% |
| Holdings | 401 | 154 |
MDY in plain words
MDY is an index equity fund tracking the S&P MidCap 400. Over the year to Sep 11, 2026 it returned +13.0% with distributions reinvested, against +17.5% for the S&P 500 and +23.0% for the Nasdaq-100. The prospectus expense ratio is 0.23% a year. By its holdings filed for Sep 10, 2026, 0% of the fund by weight is stocks the S&P 500 also holds, across 401 positions, with the top ten at 7.9%. It sat 5.3% 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, MDY or XBI?
- In the year to Sep 13, 2026, with distributions reinvested, MDY returned +13.0% and XBI returned +64.0%, so XBI returned more. One year is one year; the longer windows are in the table.
- Which is cheaper, MDY or XBI?
- MDY charges 0.23% a year and XBI charges 0.35%, so MDY is cheaper. Fees come from each fund's prospectus.
- How much do MDY and XBI overlap with the S&P 500?
- By their latest filed holdings, 0% of MDY and 8% of XBI by weight is stocks the S&P 500 already holds. Between the two funds, 4% of their books are the same securities at the same weight.
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, MDY against XBI, data as of Sep 13, 2026. https://etfiq.com/compare/any/mdy-vs-xbi Free to use with attribution; the underlying files are at Open data.
A comparison is not a recommendation. Standards and sources