IBB vs VXF: Holdings Overlap
iShares · 254 holdings · $9.3B · as of 2026-03-31
VXFVanguard Extended Market Index Fund
Vanguard · 3359 holdings · $32.2B · as of 2026-03-31
How similar are IBB and VXF?
iShares Biotechnology ETF (IBB, by iShares) holds 254 positions; Vanguard Extended Market Index Fund (VXF, by Vanguard) holds 3359. They have 204 holdings in common, and by portfolio weight the two funds are 7.7% identical. In practical terms the pair is lightly overlapping, with most of each portfolio distinct.
- Overlap by Weight
- 7.7%Sum of the smaller weight of each shared holding
- Shared Holdings
- 204IBB holds 254 · VXF holds 3359
- Weight in Shared Holdings
- IBB 51%·VXF 8%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
50 of 254 positions (48.5% of the fund) are not held by VXF. Showing the top 30 by weight.
Only in VXF
3155 of 3359 positions (92.0% of the fund) are not held by IBB. Showing the top 30 by weight.
Sector Breakdown
| Sector | IBB | VXF |
|---|---|---|
| Health Care | 91.0% | 13.3% |
| Industrials | 0.0% | 19.5% |
| Information Technology | 0.0% | 16.3% |
| Financials | 0.0% | 15.0% |
| Consumer Discretionary | 0.0% | 9.8% |
| Other Sectors | 0.0% | 23.6% |
| Unclassified | 8.9% | 2.4% |
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, 2% of VXF).
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% |
| VXF | +2.4% | +18.9% | +26.9% | +18.6% | +6.9% | +12.0% | 0.99% |
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 VXF →
Shared Holdings(204)
The top 10 shared positions account for 39% of the overlap, led by ALNY, INSM and NTRA.
 ALNYAlnylam Pharmaceuticals Inc. COM | 3.99% | 0.60% | 0.60% |
|---|---|---|---|
 INSMInsmed Inc COM PAR $.01 | 3.20% | 0.48% | 0.48% |
 NTRANatera Inc. COM | 2.41% | 0.38% | 0.38% |
 UTHRUnited Therapeutics Corporation COM | 2.30% | 0.35% | 0.35% |
 ILMNIllumina Inc COM | 1.68% | 0.26% | 0.26% |
 RVMDRevolution Medicines Inc COM | 1.54% | 0.24% | 0.24% |
 NBIXNeurocrine Biosciences Inc COM | 1.18% | 0.18% | 0.18% |
 BBIOBridgebio Pharma Inc COM | 1.13% | 0.17% | 0.17% |
 ROIVRoivant Sciences Ltd SHS | 1.24% | 0.17% | 0.17% |
 IONSIonis Pharmaceuticals, Inc. COM | 1.11% | 0.17% | 0.17% |
 EXELExelixis, Inc. COM | 0.99% | 0.15% | 0.15% |
 BMRNBiomarin Pharmaceutical Inc. COM | 0.98% | 0.15% | 0.15% |
 MEDPMedpace Holdings Inc. COM | 1.00% | 0.15% | 0.15% |
 MDGLMadrigal Pharmaceuticals Inc COM | 1.00% | 0.13% | 0.13% |
 ARWRArrowhead Pharmaceuticals Inc COM | 0.75% | 0.12% | 0.12% |
 PRAXPraxis Precision Medicines Inc COM NEW | 0.77% | 0.11% | 0.11% |
 CYTKCytokinetics Incorporated | 0.73% | 0.11% | 0.11% |
 HALOHalozyme Therapeutics Inc COM | 0.69% | 0.10% | 0.10% |
 PCVXVaxcyte Inc COM | 0.75% | 0.10% | 0.10% |
 AXSMAxsome Therapeutics Inc. COM | 0.66% | 0.10% | 0.10% |
 KRYSKrystal Biotech Inc COM | 0.60% | 0.09% | 0.09% |
 RGENRepligen Corporation COM | 0.58% | 0.09% | 0.09% |
 PTGXProtagonist Therapeutics Inc COM | 0.58% | 0.08% | 0.08% |
 COGTCogent Biosciences Inc. COM | 0.48% | 0.08% | 0.08% |
 ALKSAlkermes PLC COM USD0.01 | 0.53% | 0.08% | 0.08% |
Frequently Asked Questions
How much do IBB and VXF overlap?
IBB and VXF overlap by 7.7% of portfolio weight. They share 204 holdings (IBB holds 254 positions and VXF holds 3359), based on each fund's latest SEC-reported holdings.
Is it redundant to own both IBB and VXF?
The two portfolios are 7.7% identical by weight. Owning both is not redundant. Most of each portfolio is distinct, so the funds can serve different roles.
What are the biggest shared holdings of IBB and VXF?
The largest positions held by both funds are ALNY, INSM, NTRA, UTHR and ILMN. Together the top 10 shared positions account for 39% of the total overlap.
What does IBB own that VXF doesn't?
50 positions (48.5% of IBB) are unique to IBB, led by GILD, AMGN and VRTX. In the other direction, 3155 positions (92.0% of VXF) are unique to VXF.