MBB vs SMBS: Grades, Fees and Holdings Compared

iShares MBS ETF

MBBANasdaq

Schwab Mortgage-Backed Securities ETF

SMBSANYSE Arca

Overlap

0.0%by weight

Expense ratio

SMBS −0.01pt a year

MBB0.04%SMBS0.03%

Avg volume · 30D

MBB 4.2×the volume

MBB4.23MSMBS1.01M

MBB vs SMBS Performance

Oct 31, 2025 – Oct 30, 2026

+0.6%MBB+0.3%SMBS

Expense ratio: MBB 0.04%; SMBS 0.03%, better
Fund size: MBB $35.9B; SMBS $6.45B
1Y total return: MBB +0.6%, better; SMBS +0.3%
Yield (12M): MBB 4.42%; SMBS 5.32%, better
Holdings: MBB 10814; SMBS 4343
Avg volume (30D): MBB 4.23M sh, better; SMBS 1.01M sh
NAV per share: MBB $91.96; SMBS $24.67
52W range

ETF.net Grade

Pillar letters and Scores for MBB, SMBS, with each pillar’s weight
Pillar	MBB	SMBS
Cost30% weight	A94	A94
Mission25% weight	B56	B61Higher
Risk15% weight	D34	D35Higher
Tradability15% weight	A89Higher	B68
Holdings10% weight	A77	A86Higher
Durability5% weight	A92Higher	B60

Rank among Mortgage-Backed Securities funds

How we build Categories ›

Same Category. MBB and SMBS are both graded against the same 24 Mortgage-Backed Securities funds, so their Grades compare head to head.

Mortgage-Backed Securities⁠

Category · 24 funds

See all 24 ›

MBB ranks 2nd and SMBS 4th of 24 funds in the Mortgage-Backed Securities Category.

Rank 1ASPMBState Street SPDR Portfolio Mortgage Backed Bond ETFScore 75
Rank 2AMBBiShares MBS ETFScore 73
Rank 3AVMBSVanguard Mortgage-Backed Securities ETFScore 72
Rank 4ASMBSSchwab Mortgage-Backed Securities ETFScore 70
Rank 5BJMTGJPMorgan Mortgage-Backed Securities ETFScore 63

Our read on each fund

ETF.net Research

MBBAiShares MBS ETF

SMBSASchwab Mortgage-Backed Securities ETF

In short

MBB Launched in 2007, MBB is the plain-vanilla way to own U.S. agency mortgage bonds: one of the biggest and busiest funds in a small niche, tracking the Bloomberg U.S. MBS Index for four basis points.

SMBS No data

Stated mandate

MBB The fund seeks to track an index composed of U.S. agency mortgage-backed securities.

SMBS No data

Why people hold it

MBB Four basis points to rent the entire agency mortgage market, against a category median near 0.35%. In low-coupon bond land, that gap compounds quietly.
Scale is the real feature: one of the largest and most actively traded funds in the mortgage-bond category, which generally shows up as tighter spreads.
Pays monthly, and the mandate stays narrow: an index of U.S. agency mortgage-backed securities, nothing exotic bolted on.
Among the stronger builds in a thin peer group of mortgage-bond ETFs, on the combination of cost, trading friction and issuer staying power.

SMBS No data

Worth knowing

MBB This is one slice of the bond market. Agency mortgage paper only, with no Treasuries or corporates alongside it.
Mortgage bonds cut both ways with rates: borrowers refinance when yields fall and sit tight when they rise, so the portfolio's duration shifts underneath you.
On price it's a photo finish: SPMB tracks the same index at the same 0.04%, and VMBS runs a basis point cheaper.

SMBS No data

Full MBB profile⁠

Full SMBS profile⁠

MBB vs SMBS Holdings

How MBB and SMBS differ

Overlap by weight

0.0%

Shared holdings make up 0.0% of MBB and 0.0% of SMBS.

Level by level

Asset classFixed Income, Equity0.0%
Holdings0 in both0.0%
Countryby domicile100%

Sector

No Sector split for SMBS.

Country, concentration and asset class

Country by domicile

Country weights in MBB and SMBS, widest gap first
Country	More in MBBMore in SMBS	MBB	SMBS
United States	Same weight	100.0%	100.0%

Concentration

Weight in the 10 largest Holdings

MBB11.2%
SMBS3.9%

Securities held

MBB5,399
SMBS4,343

Asset class

MBB: Fixed Income
SMBS: Equity

Holdings

Only in MBB5,399
In both0
Only in SMBS4,343

Only in MBB

5,399 securities, 99.5% of MBB by weight

Fhlmc 30YR Umbs Super 2.00% 05/01/20511.09%
Umbs 30YR Tba(Reg A) 5.50% 11/12/20260.86%
GNMA2 30YR Tba 6.00% 11/19/20260.70%
Fnma 30YR Umbs 5.50% 09/01/20560.69%
Fnma 30YR Umbs 2.00% 12/01/20510.67%
GNMA2 30YR 5.00% 11/20/20540.59%
Fnma 30YR Umbs 2.00% 02/01/20520.56%
Fnma 30YR Umbs 2.00% 04/01/20510.56%
GNMA2 30YR 2.00% 10/20/20510.54%
GNMA2 30YR 2.00% 12/20/20510.53%
Fhlmc 30YR Umbs Super 2.00% 04/01/20510.52%
GNMA2 30YR 2.50% 07/20/20510.52%
Fnma 30YR Umbs 2.50% 11/01/20500.51%
Fnma 30YR Umbs Super 2.00% 04/01/20520.50%
Fhlmc 30YR Umbs 2.00% 02/01/20510.50%
GNMA2 30YR Tba(Reg C) 5.50% 11/19/20260.49%
Fnma 30YR Umbs 2.00% 10/01/20510.48%
Fnma 30YR Umbs 2.00% 11/01/20510.46%
Fnma 30YR Umbs 2.00% 02/01/20510.45%
GNMA2 30YR 5.00% 04/20/20560.43%
Fnma 30YR Umbs 6.00% 09/01/20540.42%
GNMA2 30YR 5.50% 09/20/20530.40%
GNMA2 30YR 5.50% 09/20/20550.40%
Fnma 30YR Umbs Super 2.00% 02/01/20520.37%
Umbs 30YR Tba(Reg A) 5.00% 11/12/20260.37%
GNMA2 30YR 2.50% 05/20/20510.35%
Fnma 30YR Umbs 6.00% 08/01/20540.35%
Fnma 30YR Umbs 2.00% 03/01/20510.35%
Fnma 30YR Umbs 2.50% 10/01/20500.34%
GNMA2 30YR Tba(Reg C) 4.50% 11/19/20260.33%
Fnma 30YR Umbs Super 3.00% 05/01/20520.33%
GNMA2 30YR 2.00% 01/20/20520.33%
Fnma 30YR Umbs 6.00% 10/01/20530.32%
GNMA2 30YR 5.00% 05/20/20560.32%
Umbs 15YR Tba(Reg B) 4.00% 11/17/20260.32%
Fhlmc 30YR Umbs 2.50% 01/01/20510.31%
Fhlmc 30YR Umbs 5.00% 05/01/20560.31%
GNMA2 30YR 2.50% 08/20/20510.30%
GNMA2 30YR Tba(Reg C) 5.00% 11/19/20260.30%
Fnma 30YR Umbs 2.50% 03/01/20520.30%
Fnma 30YR Umbs 2.50% 07/01/20510.29%
Umbs 30YR Tba(Reg A) 6.00% 11/12/20260.29%
Fhlmc 30YR Umbs Super 2.00% 06/01/20520.29%
Fhlmc 30YR Umbs Super 6.00% 10/01/20540.28%
Fnma 30YR Umbs 5.00% 05/01/20560.28%
GNMA2 30YR 2.00% 12/20/20500.28%
Fhlmc 30YR Umbs Super 2.00% 12/01/20510.28%
Fnma 30YR Umbs Super 2.00% 10/01/20520.28%
GNMA2 30YR 2.50% 12/20/20510.27%
Fhlmc 30YR Umbs 2.00% 11/01/20510.27%

Only in SMBS

4,343 securities, 100% of SMBS by weight

Ssc Government Mm Gvmxx1.31%
GNMA2 30YR 5.00% 11/20/2054 (BBG01NZQMR80)0.44%
Fhlmc 30YR Umbs Super 5.50% 10/01/2054 (BBG01NYFN109)0.32%
Fhlmc 30YR Umbs Super 2.50% 01/01/2054 (BBG020YCJVV0)0.31%
Fhlmc 30YR Umbs 5.00% 04/01/2056 (BBG01ZQXS4M7)0.29%
Fhlmc 30YR Umbs Super 2.00% 02/01/2052 (BBG013B19FS4)0.28%
Fnma 30YR Umbs 5.50% 04/01/2053 (BBG01F33L1J9)0.25%
GNMA2 30YR 5.00% 05/20/2056 (BBG01ZVZ4RL2)0.25%
Fnma 30YR Umbs 2.00% 05/01/2051 (BBG00ZHCZ133)0.24%
Fhlmc 30YR Umbs Super 2.00% 11/01/2050 (BBG00WGK3T46)0.24%
GNMA2 30YR 5.00% 01/20/2056 (BBG01XK7V325)0.24%
Fhlmc 30YR Umbs 5.00% 03/01/2056 (BBG01YX6GQM5)0.23%
GNMA2 30YR 5.00% 07/20/2056 (BBG0218B7LX2)0.23%
GNMA2 30YR 5.00% 12/20/2055 (BBG01WXTXHP7)0.22%
Fhlmc 30YR Umbs Super 2.50% 01/01/2052 (BBG016008MY0)0.21%
GNMA2 30YR 5.50% 06/20/2055 (BBG01SJ8MLF2)0.20%
GNMA2 30YR 5.00% 04/20/2056 (BBG01Z997ZP0)0.20%
GNMA2 30YR 5.00% 11/20/2055 (BBG01WCVFMG4)0.19%
Fhlmc 30YR Umbs 5.00% 03/01/2056 (BBG021983ZP0)0.19%
Fhlmc 30YR Umbs Super 2.00% 02/01/2051 (BBG00Y2HT9V0)0.19%
GNMA2 30YR 5.00% 10/20/2053 (BBG01H70ZSP6)0.19%
Fhlmc 30YR Umbs 6.00% 08/01/2055 (BBG01VH3BJN6)0.18%
Fnma 30YR Umbs 1.50% 01/01/2051 (BBG00Y2N8VB3)0.18%
GNMA2 30YR 2.00% 01/20/2051 (BBG00XM8VJ81)0.18%
Fnma 30YR Umbs Super 5.50% 03/01/2056 (BBG02149FF01)0.18%
GNMA2 30YR 5.50% 04/20/2054 (BBG01KRRJJN8)0.18%
GNMA2 30YR 5.00% 12/20/2054 (BBG01PH23K11)0.18%
Fhlmc 30YR Umbs Super 4.50% 12/01/2054 (BBG01Q51M614)0.17%
GNMA2 30YR 4.00% 09/20/2052 (BBG017RS0430)0.17%
GNMA2 30YR 2.00% 11/20/2050 (BBG00WC0HNK4)0.17%
GNMA2 30YR 5.00% 01/20/2055 (BBG01Q0N1RB7)0.17%
Fhlmc 30YR Umbs Super 5.00% 12/01/2052 (BBG019M600Y3)0.17%
GNMA2 30YR 2.00% 02/20/2051 (BBG00XZZP6J0)0.17%
Fnma 30YR Umbs Super 3.00% 08/01/2051 (BBG01249GBZ0)0.17%
Fnma 30YR Umbs Super 2.50% 04/01/2052 (BBG01H6YXH06)0.17%
Fnma 30YR Umbs 2.00% 02/01/2051 (BBG00YHWVS82)0.17%
Fnma 30YR Umbs Super 4.50% 01/01/2054 (BBG01NRW0XJ5)0.17%
Fnma 30YR Umbs Super 4.00% 08/01/2052 (BBG0194C3RZ7)0.17%
Fhlmc 30YR Umbs Super 2.00% 03/01/2051 (BBG00YDFS7Y4)0.17%
Fhlmc 30YR Umbs Super 5.50% 09/01/2055 (BBG01XH7PCY1)0.16%
Fnma 30YR Umbs 2.00% 07/01/2051 (BBG01107SVX5)0.16%
Fhlmc 30YR Umbs Super 2.00% 07/01/2051 (BBG01TG2L1Z9)0.16%
Fnma 30YR Umbs 6.00% 04/01/2055 (BBG01S4FGCM1)0.16%
GNMA2 30YR 2.00% 04/20/2051 (BBG00YPHW6M7)0.16%
GNMA2 30YR 2.50% 08/20/2050 (BBG00TGXYGY6)0.16%
Fnma 30YR Umbs 2.00% 12/01/2050 (BBG00XS6NZ55)0.16%
GNMA2 30YR 4.50% 10/20/2052 (BBG018GZYKB2)0.16%
GNMA2 30YR 5.50% 08/20/2054 (BBG01MLZDQL4)0.16%
Fnma 30YR Umbs 6.00% 02/01/2054 (BBG01KFL4C28)0.16%
GNMA2 30YR 5.50% 12/20/2054 (BBG01PH23JP8)0.16%

Weight gaps

MBB and SMBS share no securities.

All 10,833 MBB holdings⁠All 4,343 SMBS holdings⁠

How we measure overlap

Each holding counts at its smaller weight in the two funds, summed over the full Holdings. Sector, country and asset class use the same rule on each fund’s split. Cash, FX and derivative lines stay out of the counts. Two bond funds get no overlap figure.

MBB vs SMBS Cost

Overpaying MBB vs SMBS

$211

On $10,000 over 30 years. 7% growth a year before fees, expense ratio only.

MBB 0.04%
$849
SMBS 0.03%
$638

Amount$10,000

Years30 years

Cost over time

MBB 0.04%
SMBS 0.03%
Overpaying

Year by year

Year	MBB	SMBS	Overpaying
10	$73	$55	$18
20	$288	$216	$72
30	$849	$638	$211

Expense ratio

0.04%MBB
0.03%SMBS, cheaper

SMBS0.03%MBB0.04%

0.03%0.86%

Middle half of Mortgage-Backed Securities funds
Median 0.38%

SMBS cheapest of 24 funds

MBB 3rd cheapest of 24 funds

MBB vs SMBS Dividends

Last 12 months to Oct 30, 2026

Yield (12M): MBB 4.42%; SMBS 5.32%, better
Payout (12M): MBB $4.07; SMBS $1.31
Last payment: MBB $0.37; SMBS $0.11
Ex-dividend: MBB Oct 1, 2026; SMBS Oct 1, 2026
Paid on: MBB Oct 6, 2026; SMBS Oct 7, 2026
Frequency: MBB Monthly; SMBS Monthly

Distribution history

Per share, 2023 to 2026, same scale for both

MBBMonthly · 45 paymentsAll MBB payments⁠

SMBSMonthly · 22 paymentsAll SMBS payments⁠

MBB vs SMBS Risk

Fall from peak · 5 years

This chart needs five years of history for both funds.

Risk facts

VolatilityStd dev, 3 years: MBB 6.4%SMBS 4.9%since Dec 2024
Return per unit of riskSharpe ratio, 3 years: MBB 0.30SMBS −0.16since Dec 2024
Worst fallMax drawdown, 5 years: MBB −16.8%SMBS −5.2%since Nov 2024
Market sensitivityBeta, 5 years: MBB 1.14SMBS 0.07; Market = 1

MBB and SMBS in the news

All news⁠

New ETFs
GMO's ETF share class costs more than the fund's $35 million Class III shares
Oct 22, 2026MBB
First-Year Review
Nuveen's securitized-income ETF returned 4.2% in year one, almost all from coupons
Sep 23, 2026MBB
News
Existing-home sales fall below 4 million as yields hit a 52-week high
Sep 10, 2026MBB

Popular comparisons

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MBBAvsVMBSA
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MBBAvsJMTGB
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MBB vs SMBS

In short

Stated mandate

Why people hold it

Worth knowing

How MBB and SMBS differ

Level by level

Sector

Country, concentration and asset class

Country by domicile

Concentration

Asset class

Holdings

Only in MBB

Only in SMBS

Weight gaps

Cost over time

Year by year

Distribution history

Fall from peak · 5 years

Risk facts

GMO's ETF share class costs more than the fund's $35 million Class III shares

Nuveen's securitized-income ETF returned 4.2% in year one, almost all from coupons

Existing-home sales fall below 4 million as yields hit a 52-week high

How MBB and SMBS differ

Level by level

Sector

Country, concentration and asset class

Country by domicile

Concentration

Asset class

Holdings

Only in MBB

Only in SMBS

Weight gaps