MDY vs XBI: Holdings Overlap
MDYState Street® SPDR® S&P MIDCAP 400® ETF Trust
State Street (SPDR) · 399 holdings · $27.1B · as of 2026-08-06
XBIState Street® SPDR® S&P® Biotech ETF
State Street (SPDR) · 149 holdings · $10.0B · as of 2026-08-06
How similar are MDY and XBI?
State Street® SPDR® S&P MIDCAP 400® ETF Trust (MDY, by State Street (SPDR)) holds 399 positions; State Street® SPDR® S&P® Biotech ETF (XBI, by State Street (SPDR)) holds 149. They have 9 holdings in common, and by portfolio weight the two funds are 3.6% identical. In practical terms the pair is essentially distinct, holding almost none of the same securities.
- Overlap by Weight
- 3.6%Sum of the smaller weight of each shared holding
- Shared Holdings
- 9MDY holds 399 · XBI holds 149
- Weight in Shared Holdings
- MDY 4%·XBI 10%Share of each fund's weight in stocks both funds own
Based on each fund's latest official holdings. How is this calculated?
What makes each fund different
Only in MDY
390 of 399 positions (101.5% of the fund) are not held by XBI. Showing the top 30 by weight.
Only in XBI
140 of 149 positions (90.4% of the fund) are not held by MDY. Showing the top 30 by weight.
Sector Breakdown
| Sector | MDY | XBI |
|---|---|---|
| Health Care | 10.3% | 95.5% |
| Industrials | 25.9% | 0.0% |
| Financials | 16.0% | 0.0% |
| Information Technology | 15.6% | 0.0% |
| Consumer Discretionary | 11.6% | 0.0% |
| Other Sectors | 25.7% | 0.0% |
| Unclassified | 0.0% | 4.6% |
Share of each fund's portfolio weight by GICS-style sector, compiled from issuer fund data and our own classification of the holdings, not the issuers' published sector charts. “Unclassified” is weight we could not classify (0% of MDY, 5% of XBI).
Performance
| Fund | 1M | YTD | 1Y | 3Y (ann.) | 5Y (ann.) | 10Y (ann.) | Yield |
|---|---|---|---|---|---|---|---|
| MDY | +3.1% | +18.1% | +25.6% | +14.2% | +8.8% | +10.9% | 0.99% |
| XBI | -4.0% | +29.2% | +85.3% | +26.3% | +4.5% | +9.5% | 0.36% |
Total returns including dividends, from adjusted daily closes as of 2026-08-07. 3Y/5Y/10Y are annualized. Yield is trailing-12-month distributions over the last close. Past performance does not predict future results.
Project the growth of $10,000 in MDY vs XBI →
Shared Holdings(9)
The top 9 shared positions account for 100% of the overlap, led by BMRN, UTHR and NBIX.
 BMRNBiomarin Pharmaceutical Inc. COM | 0.64% | 1.06% | 0.64% |
|---|---|---|---|
 UTHRUnited Therapeutics Corporation COM | 0.62% | 0.95% | 0.62% |
 NBIXNeurocrine Biosciences Inc COM | 0.44% | 0.96% | 0.44% |
 ROIVRoivant Sciences Ltd SHS | 0.43% | 1.19% | 0.43% |
 EXELExelixis, Inc. COM | 0.36% | 0.96% | 0.36% |
 ARWRArrowhead Pharmaceuticals Inc COM | 0.33% | 1.17% | 0.33% |
 CYTKCytokinetics Incorporated | 0.30% | 1.17% | 0.30% |
 HALOHalozyme Therapeutics Inc COM | 0.28% | 1.18% | 0.28% |
 KRYSKrystal Biotech Inc COM | 0.23% | 1.00% | 0.23% |
Frequently Asked Questions
How much do MDY and XBI overlap?
MDY and XBI overlap by 3.6% of portfolio weight. They share 9 holdings (MDY holds 399 positions and XBI holds 149), based on each fund's latest SEC-reported holdings.
Is it redundant to own both MDY and XBI?
The two portfolios are 3.6% identical by weight. Owning both is genuine diversification: the funds hold almost none of the same securities.
What are the biggest shared holdings of MDY and XBI?
The largest positions held by both funds are BMRN, UTHR, NBIX, ROIV and EXEL. Together the top 9 shared positions account for 100% of the total overlap.
What does MDY own that XBI doesn't?
390 positions (101.5% of MDY) are unique to MDY, led by ATI, TWLO and ILMN. In the other direction, 140 positions (90.4% of XBI) are unique to XBI.