MDY vs XBI: how much do they overlap?
SPDR S&P MIDCAP 400 ETF Trust (MDY) · SPDR S&P Biotech ETF (XBI)
overlap by weight · 8 shared holdings
MDY: 400 holdings (as of 09-Jul-2026) · XBI: 149 holdings (as of 09-Jul-2026)
Low overlap
What this means
MDY and XBI hold mostly different stocks. Combining them genuinely spreads your exposure across different parts of the market.
Overlap by weight sums the smaller of the two funds' weights for every stock they both hold — it answers "how much of my money is in the same stocks either way?" See methodology.
Top shared holdings
| Company | Ticker | in MDY | in XBI |
|---|---|---|---|
| United Therapeutics Corporation | UTHR | 0.65% | 0.91% |
| Neurocrine Biosciences Inc. | NBIX | 0.5% | 1% |
| Roivant Sciences Ltd. | ROIV | 0.46% | 1.16% |
| Exelixis Inc. | EXEL | 0.4% | 0.97% |
| Arrowhead Pharmaceuticals Inc. | ARWR | 0.33% | 1.06% |
| Cytokinetics Incorporated | CYTK | 0.32% | 1.15% |
| Biomarin Pharmaceutical Inc. | BMRN | 0.32% | 0.95% |
| Halozyme Therapeutics Inc. | HALO | 0.26% | 1% |
FAQ
How much do MDY and XBI overlap?
MDY and XBI have a 3.2% overlap by weight, sharing 8 holdings (out of 400 in MDY and 149 in XBI), based on official issuer holdings as of 09-Jul-2026.
What does 3.2% overlap mean?
MDY and XBI hold mostly different stocks. Combining them genuinely spreads your exposure across different parts of the market.
Which stocks do MDY and XBI both hold?
The largest shared positions are United Therapeutics Corporation, Neurocrine Biosciences Inc., Roivant Sciences Ltd., Exelixis Inc., Arrowhead Pharmaceuticals Inc.. The full list of top shared holdings with weights in each fund is shown on this page.