IBB vs IWO: Holdings Overlap
iShares · 254 holdings · $9.3B · as of 2026-03-31
IWOiShares Russell 2000 Growth ETF
iShares · 1101 holdings · $14.8B · as of 2026-03-31
How similar are IBB and IWO?
iShares Biotechnology ETF (IBB, by iShares) holds 254 positions; iShares Russell 2000 Growth ETF (IWO, by iShares) holds 1101. They have 110 holdings in common, and by portfolio weight the two funds are 12.5% identical. In practical terms the pair is lightly overlapping, with most of each portfolio distinct.
- Overlap by Weight
- 12.5%Sum of the smaller weight of each shared holding
- Shared Holdings
- 110IBB holds 254 · IWO holds 1101
- Weight in Shared Holdings
- IBB 21%·IWO 13%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
144 of 254 positions (78.6% of the fund) are not held by IWO. Showing the top 30 by weight.
Only in IWO
991 of 1101 positions (87.3% of the fund) are not held by IBB. Showing the top 30 by weight.
Sector Breakdown
| Sector | IBB | IWO |
|---|---|---|
| Health Care | 91.0% | 23.1% |
| Industrials | 0.0% | 23.7% |
| Information Technology | 0.0% | 19.0% |
| Financials | 0.0% | 8.6% |
| Consumer Discretionary | 0.0% | 7.3% |
| Other Sectors | 0.0% | 14.1% |
| Unclassified | 8.9% | 4.0% |
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, 4% of IWO).
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% |
| IWO | +1.2% | +21.0% | +34.7% | +17.5% | +5.9% | +11.0% | 0.42% |
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 IWO →
Shared Holdings(110)
The top 10 shared positions account for 37% of the overlap, led by BBIO, MDGL and ARWR.
 BBIOBridgebio Pharma, Inc. | 1.13% | 0.79% | 0.79% |
|---|---|---|---|
 MDGLMadrigal Pharmaceuticals, Inc. | 1.00% | 0.60% | 0.60% |
 ARWRArrowhead Pharmaceuticals, Inc. | 0.75% | 0.57% | 0.57% |
 AXSMAxsome Therapeutics, Inc. | 0.66% | 0.47% | 0.47% |
 KRYSKrystal Biotech, Inc. | 0.60% | 0.43% | 0.43% |
 PTGXProtagonist Therapeutics, Inc. | 0.58% | 0.41% | 0.41% |
 COGTCogent Biosciences, Inc. | 0.48% | 0.35% | 0.35% |
| Nuvalent, Inc., Class A | 0.45% | 0.34% | 0.34% |
 XENEXenon Pharmaceuticals, Inc. | 0.43% | 0.34% | 0.34% |
 KYMRKymera Therapeutics, Inc. | 0.53% | 0.32% | 0.32% |
 RYTMRhythm Pharmaceuticals, Inc. | 0.51% | 0.31% | 0.31% |
 ACLXArcellx, Inc. | 0.47% | 0.29% | 0.29% |
 PTCTPTC Therapeutics, Inc. | 0.50% | 0.29% | 0.29% |
 AM6Amicus Therapeutics, Inc. | 0.41% | 0.29% | 0.29% |
 ALKSAlkermes plc | 0.53% | 0.29% | 0.29% |
 CGONCG oncology, Inc. | 0.32% | 0.27% | 0.27% |
 SRRKScholar Rock Holding Corp. | 0.36% | 0.26% | 0.26% |
 MIRMMirum Pharmaceuticals, Inc. | 0.45% | 0.26% | 0.26% |
 APGEApogee Therapeutics, Inc. | 0.37% | 0.25% | 0.25% |
 CRNXCrinetics Pharmaceuticals, Inc. | 0.32% | 0.24% | 0.24% |
 TWSTTwist Bioscience Corp. | 0.26% | 0.19% | 0.19% |
 ACADACADIA Pharmaceuticals, Inc. | 0.34% | 0.19% | 0.19% |
 TARSTarsus Pharmaceuticals, Inc. | 0.26% | 0.19% | 0.19% |
 ARQTArcutis Biotherapeutics, Inc. | 0.24% | 0.17% | 0.17% |
 VCYTVeracyte, Inc. | 0.23% | 0.17% | 0.17% |
Frequently Asked Questions
How much do IBB and IWO overlap?
IBB and IWO overlap by 12.5% of portfolio weight. They share 110 holdings (IBB holds 254 positions and IWO holds 1101), based on each fund's latest SEC-reported holdings.
Is it redundant to own both IBB and IWO?
The two portfolios are 12.5% 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 IWO?
The largest positions held by both funds are BBIO, MDGL, ARWR, AXSM and KRYS. Together the top 10 shared positions account for 37% of the total overlap.
What does IBB own that IWO doesn't?
144 positions (78.6% of IBB) are unique to IBB, led by GILD, AMGN and VRTX. In the other direction, 991 positions (87.3% of IWO) are unique to IWO.