Data as of Oct 28, 2026.
MBB vs XBI: Differences, Returns & Fees
Over the year to Oct 28, 2026, MBB returned −0.8% to XBI's +41.2%, and MBB charges 0.04% to XBI's 0.35%.
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Net assets: $35.5bn on Oct 28, 2026 for iShares MBS ETF, and $10.3bn on Oct 27, 2026 for State Street SPDR S&P Biotech ETF.
Pair scorecard
MBB costs 0.31 points a year less; their one-year returns differ by 42.0 points; MBB is 3.5 times larger.
| Measure | MBB | XBI |
|---|---|---|
| Return | ||
| Total return, 1 year | −0.8% | +41.2% |
| Drawdown | ||
| Below its all-time high | 8.9%, high on Feb 8, 2021 | |
| Benchmark | ||
| What it tracks | Bloomberg U.S. MBS Index | Biotech |
| Cost and size | ||
| Expense ratio | 0.04% | 0.35% |
| Net assets, as of Oct 26, 2026 | $35.6bn | $10.2bn |
| Active share vs the S&P 500 | 98% | |
| Holdings | ||
| Holdings in common | 0% | |
| In the S&P 500, by weight | 13% | |
| Top ten holdings, share of the fund | 18% | |
Holdings in common uses holdings dated Oct 27, 2026. Method
Risk and return
Mar 23, 2007 to Oct 23, 2026 · 1,022 weekly returnsXBI returned more: +891.2% to +63.4%. MBB swung less: 4.2% to 29.6%. MBB fell less at its worst: −17.4% to −61.5%.
Full scorecard
9 measures, with how each is measured Open ↓
| Measure | MBB | XBI | Edge | How it is measured |
|---|---|---|---|---|
| Return | ||||
| Total return | +63.4% | +891.2% | XBI | Price change plus distributions, reinvested. |
| Annualized | +2.5% | +12.4% | XBI | Total return as a yearly rate. |
| Price return | −9.6% | +837.2% | XBI | Price change alone, distributions left out. |
| Risk | ||||
| Volatility | 4.2% | 29.6% | MBB | Spread of weekly returns, annualized. Lower is steadier. |
| Downside deviation | 2.9% | 20.2% | MBB | Like volatility, counting only weeks below the Treasury bill rate. |
| Max drawdown | −17.4% | −61.5% | MBB | Deepest fall from a high to the low after it. |
| Risk-adjusted | ||||
| Sharpe | 0.24 | 0.49 | XBI | Return above Treasury bills per unit of volatility. |
| Sortino | 0.35 | 0.72 | XBI | Return above Treasury bills per unit of downside deviation. |
| Calmar | 0.15 | 0.20 | XBI | Annualized return divided by the max drawdown. |
Computed by ETFIQ from Tiingo daily prices and ETFIQ's distribution records, 1,022 weekly returns. Cash rate: the 13-week Treasury bill.
What they share
By the books each fund has filed, MBB and XBI hold 0% of their money in the same securities at the same weight. Holdings dated Oct 27, 2026.
half
0% in common
Only in one fund ↓
Side by side
MBB and XBI on the fields both publish, as of Oct 28, 2026. Source: ETFIQ.
MBB and XBI do different jobs. What does each one do in a portfolio?
- What each follows. MBB follows Bloomberg U.S. MBS Index and XBI follows Biotech.
- Holdings in common. 0% of the weight is in the same securities (holdings dated Oct 27, 2026).
- One-year total return. Over 1 year to Oct 28, 2026 MBB returned −0.8% and XBI +41.2% with distributions reinvested, a gap of 42.0 points.
Data as of Oct 28, 2026.
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MBB
MBB tracks an index of mortgage-backed securities. Over the year to Oct 28, 2026 it returned −0.8% with distributions reinvested, against −1.1% for its benchmark, the Bloomberg U.S. MBS Index. The prospectus expense ratio is 0.04% a year.
XBI
By weight, 13% of XBI's portfolio is stocks that are also in the S&P 500; its active share against the S&P 500 is 98%. The top ten holdings are 18% of the fund across 165 positions, as published by its issuer for Oct 27, 2026. Over the year to Oct 28, 2026 the fund returned +41.2% with distributions reinvested. It sits 8.9% below its all-time high of Feb 8, 2021.
Questions people ask
- Are MBB and XBI in the same category?
- MBB is a bond ETF and XBI is a thematic ETF, so they do different jobs. The table compares what both publish: return, cost and holdings.
- Which returned more over the last year, MBB or XBI?
- In the year to Oct 28, 2026, with distributions reinvested, MBB returned −0.8% and XBI +41.2%.
- Which is cheaper, MBB or XBI?
- MBB is cheaper, by 0.31 percentage points a year. That is about $31 on $10,000 held for a year. Fees come from each fund's prospectus.
Links are sources, not endorsements. A comparison is not a recommendation.
How this is computed
Overlap adds up the smaller of the two weights for each security both funds hold.
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ETFIQ, MBB against XBI, data as of Oct 28, 2026. https://etfiq.com/compare/any/mbb-vs-xbi
ETFIQ. (Oct 28, 2026). MBB against XBI. Retrieved from https://etfiq.com/compare/any/mbb-vs-xbi
[MBB against XBI (ETFIQ, Oct 28, 2026)](https://etfiq.com/compare/any/mbb-vs-xbi)
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