⚖️ XBI vs IBB Comparison · Free & No Signup

XBI vs IBB: Equal-Weight Small Biotech vs Large-Cap Biotech — Big Difference

XBI weights each biotech equally — more small-cap exposure, higher volatility, bigger potential swings. IBB concentrates in mega-cap names like Amgen and Gilead. Same sector, very different funds.

💰 XBI is cheaper 🔬 Compare top 10 holdings → 💡 Plain-English verdict

🤝 BFF Take

XBI for Small-Cap Biotech Bets — IBB for Large-Cap Biotech Stability

XBI (SPDR S&P Biotech ETF) and IBB (iShares Biotechnology ETF) both target US biotech but with dramatically different approaches. XBI uses equal weighting across ~130 stocks — giving small clinical-stage biotechs the same weight as billion-dollar companies. This makes XBI much more volatile but also more sensitive to small-cap biotech catalyst events (FDA approvals, trial results). IBB is market-cap weighted, so Amgen, Gilead, and Regeneron dominate — giving it more large-cap stability. XBI costs 0.35%; IBB costs 0.44%. XBI is for traders and aggressive investors who want full biotech exposure including small-caps. IBB is for investors who want biotech exposure weighted toward established revenue-generating companies.

📋 Quick Takeaways

⚗️XBI equal-weights ~130 biotechs — small-cap clinical-stage companies get equal influence as large caps

🏢IBB market-cap weights — Amgen, Gilead, Regeneron dominate; more like large-cap pharma than pure biotech

💰XBI costs 0.35% vs IBB's 0.44% — XBI is also cheaper with broader small-cap exposure

📊 Data-Based Take: XBI has the lower fee

Whether the lower-cost fund suits your situation depends on your existing holdings, account type, tax situation, and how you use each fund. This is a cost comparison, not a personalized recommendation.

✓ Reviewed by a CFA® Charterholder · Data as of Jul 14, 2026 · Educational only, not financial advice

XBI

State Street SPDR S&P Biotech ETF

Expense Ratio

0.35% ✓

1-Year Return

+80.2%

AUM

$10.7B

Holdings

130

IBB

iShares Biotechnology ETF

Expense Ratio

0.44%

1-Year Return

+45.6%

AUM

$9.1B

Holdings

220

📋 XBI vs IBB — Key Facts Side by Side

Metric	XBI	IBB
Fund Name	State Street SPDR S&P Biotech ETF	iShares Biotechnology ETF
Issuer	State Street	iShares
Tracks Index	S&P Biotechnology Select Industry	NYSE Arca Biotechnology
Expense Ratio	0.35% ✓	0.44%
Cost per $10K/yr	$35.00	$44.00
AUM	$10.7B	$9.1B
Holdings	130	220
Inception	2006	2001
1-Year Return	+80.16%	+45.62%
3-Year Return	+26.44%	+16.96%
5-Year Return	+4.32%	+4.16%
Dividend Yield	0.36%	0.22%
Holdings Overlap	See holdings overlap →
Avg Bid-Ask Spread	0.01%	0.01%

Expense ratio, AUM, and returns updated Jul 14, 2026 from ETF BFF database. Returns are annualised. Not investment advice.

📊 XBI vs IBB — Annualised Returns

Annualised returns (trailing, price-based). Past performance does not guarantee future results.

🎯 Which Fund Fits Which Investor?

Often fits investors who...

XBI

want the lowest fees: saves ~$9/yr per $10K vs IBB
already use State Street and prefer staying within one fund family

Often fits investors who...

IBB

want broader diversification (220 holdings vs 130)
already use iShares and prefer staying within one fund family

💰 What the Fee Difference Actually Costs

Adjust the numbers for your situation. This models each fund's expense ratio compounding against your balance over time.

Investment amount$ Years held Expected annual return%

Assumes a constant annual return reinvested, with each fund's expense ratio deducted yearly. Illustrative only; actual returns vary. Past performance does not guarantee future results.

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❓ XBI vs IBB — Frequently Asked Questions

What is the main difference between XBI and IBB?

The key difference is weighting methodology. XBI uses equal weighting — every stock in the index gets roughly the same allocation. This means a tiny clinical-stage biotech with no revenue has the same weight as Amgen. IBB uses market-cap weighting — larger companies get larger allocations. This makes IBB behave more like a large-cap healthcare ETF, while XBI is a purer bet on the entire biotech ecosystem including small companies.

Which is more volatile — XBI or IBB?

XBI is consistently more volatile than IBB due to its equal-weight approach giving meaningful exposure to small-cap and clinical-stage biotechs. A single FDA approval or rejection in a small holding can cause XBI to spike or crash 2-5% in a day. IBB's large-cap dominance dampens individual stock impacts. In biotech bull markets, XBI typically outperforms; in biotech bear markets, XBI falls harder.

Is biotech a good long-term investment?

Biotech has been one of the most volatile sector ETFs over the past decade, with massive boom-bust cycles tied to drug approvals, clinical trial results, and interest rate sensitivity (biotech companies often burn cash and rely on capital markets). The long-term demographic and innovation tailwinds are real, but execution risk in individual companies is high. Both XBI and IBB have lagged the S&P 500 over most 5 and 10-year periods despite the compelling sector narrative.

Does IBB or XBI pay dividends?

Neither XBI nor IBB pays meaningful dividends. Biotech companies reinvest capital into R&D rather than distributions. Any dividend yield on these ETFs is incidental and very small. They are total-return vehicles driven almost entirely by price appreciation (or decline) rather than income.

What are the biggest holdings in XBI vs IBB?

In IBB, the top holdings are large-caps: Amgen, Gilead Sciences, Regeneron, Vertex Pharmaceuticals, and Moderna typically make up 30-40% of the fund. In XBI, no single stock exceeds 2-3% due to equal weighting — the top positions are often mid-cap or small-cap names that rotate frequently based on rebalancing. This makes XBI much harder to predict from a holdings perspective.

New to ETF investing? See answers to the most common ETF questions →

📄 XBI & IBB Fact Sheets

XBI Fact Sheet→ IBB Fact Sheet→

ℹ️ Data shown is for educational purposes and may not reflect the most current figures. Returns are trailing price-based and exclude dividend reinvestment. Past performance does not guarantee future results. ETF BFF is not a licensed financial advisor — this is not personalized financial advice.