IBB vs XBI: Holdings Overlap
iShares · 254 holdings · $9.3B · as of 2026-03-31
XBIState Street® SPDR® S&P® Biotech ETF
State Street (SPDR) · 149 holdings · $10.0B · as of 2026-08-06
Holdings snapshots are 128 days apart (IBB: 2026-03-31, XBI: 2026-08-06). Weights and index membership change between snapshots, so the true current overlap is typically higher than shown. For funds tracking the same index, the gap can be 5–15 points.
How similar are IBB and XBI?
iShares Biotechnology ETF (IBB, by iShares) holds 254 positions; State Street® SPDR® S&P® Biotech ETF (XBI, by State Street (SPDR)) holds 149. They have 123 holdings in common, and by portfolio weight the two funds are 39.3% identical. In practical terms the pair is moderately overlapping; they share a meaningful core, but each fund adds distinct exposure.
- Overlap by Weight
- 39.3%Sum of the smaller weight of each shared holding
- Shared Holdings
- 123IBB holds 254 · XBI holds 149
- Weight in Shared Holdings
- IBB 76%·XBI 87%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 IBB
131 of 254 positions (24.0% of the fund) are not held by XBI. Showing the top 30 by weight.
Sector Breakdown
| Sector | IBB | XBI |
|---|---|---|
| Health Care | 91.0% | 95.5% |
| Other Sectors | 0.0% | 0.0% |
| Unclassified | 8.9% | 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 (9% of IBB, 5% of XBI).
Performance
| Fund | 1M | YTD | 1Y | 3Y (ann.) | 5Y (ann.) | 10Y (ann.) | Yield |
|---|---|---|---|---|---|---|---|
| IBB | -0.3% | +17.3% | +51.0% | +16.4% | +3.1% | +7.4% | 0.21% |
| 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 IBB vs XBI →
Shared Holdings(123)
The top 10 shared positions account for 30% of the overlap, led by INSM, RVMD and REGN.
 INSMInsmed Inc COM PAR $.01 | 3.20% | 1.39% | 1.39% |
|---|---|---|---|
 RVMDRevolution Medicines Inc COM | 1.54% | 1.33% | 1.33% |
 REGNRegeneron Pharmaceuticals, Inc. COM | 7.21% | 1.24% | 1.24% |
 ROIVRoivant Sciences Ltd SHS | 1.24% | 1.19% | 1.19% |
 NTRANatera Inc. COM | 2.41% | 1.18% | 1.18% |
 AMGNAmgen Inc. COM | 7.51% | 1.16% | 1.16% |
 BBIOBridgebio Pharma Inc COM | 1.13% | 1.19% | 1.13% |
 MRNAModerna Inc COM | 1.68% | 1.13% | 1.13% |
 INCYIncyte Corporation. COM | 1.70% | 1.09% | 1.09% |
 VRTXVertex Pharmaceuticals Incorporated COM | 7.44% | 1.07% | 1.07% |
 GILDGilead Sciences Inc. COM | 7.75% | 1.04% | 1.04% |
 BIIBBiogen Inc COM | 2.46% | 1.03% | 1.03% |
 MDGLMadrigal Pharmaceuticals Inc COM | 1.00% | 1.05% | 1.00% |
 BMRNBiomarin Pharmaceutical Inc. COM | 0.98% | 1.06% | 0.98% |
 NBIXNeurocrine Biosciences Inc COM | 1.18% | 0.96% | 0.96% |
 EXELExelixis, Inc. COM | 0.99% | 0.96% | 0.96% |
 UTHRUnited Therapeutics Corporation COM | 2.30% | 0.95% | 0.95% |
 PRAXPraxis Precision Medicines Inc COM NEW | 0.77% | 1.49% | 0.77% |
 ARWRArrowhead Pharmaceuticals Inc COM | 0.75% | 1.17% | 0.75% |
 PCVXVaxcyte Inc COM | 0.75% | 1.25% | 0.75% |
 CYTKCytokinetics Incorporated | 0.73% | 1.17% | 0.73% |
 IONSIonis Pharmaceuticals, Inc. COM | 1.11% | 0.72% | 0.72% |
 ALNYAlnylam Pharmaceuticals Inc. COM | 3.99% | 0.72% | 0.72% |
 HALOHalozyme Therapeutics Inc COM | 0.69% | 1.18% | 0.69% |
 KRYSKrystal Biotech Inc COM | 0.60% | 1.00% | 0.60% |
Frequently Asked Questions
How much do IBB and XBI overlap?
IBB and XBI overlap by 39.3% of portfolio weight. They share 123 holdings (IBB holds 254 positions and XBI holds 149), based on each fund's latest SEC-reported holdings.
Is it redundant to own both IBB and XBI?
The two portfolios are 39.3% identical by weight. Owning both is defensible: they share a meaningful core, but each fund adds exposure the other lacks.
What are the biggest shared holdings of IBB and XBI?
The largest positions held by both funds are INSM, RVMD, REGN, ROIV and NTRA. Together the top 10 shared positions account for 30% of the total overlap.
What does IBB own that XBI doesn't?
131 positions (24.0% of IBB) are unique to IBB, led by ARGX, ONC and ILMN. In the other direction, 26 positions (13.3% of XBI) are unique to XBI.