ETF comparison
IUSB vs MBB
Both US Aggregate Bond.
Holdings overlap
1,215 positions appear in both funds. Buying equal dollars of IUSB and MBB would leave roughly 9.0% of each dollar exposed to the same underlying securities.
Unmatched is the part of a fund's weight the other fund doesn't match: names only it holds, plus any extra weight it puts in names both funds hold.
Side by side
Sub-score comparison
Tracking quality isn't part of the composite — see what we don't score for why.
Cost difference
MBB is 2 bps cheaper than IUSB. On a $100,000 position that's about $20/yr more in fees for IUSB.
Fee figure is the annual expense charged on $100,000. To see how the gap compounds over a multi-decade holding period, open the cost calculator pre-filled with IUSB vs MBB.
Top shared holdings
1,215 shared in total| # | Holding | In IUSB | In MBB | Overlap |
|---|---|---|---|---|
| 1 | Government National Mortgage Association | 0.18% | 0.16% | 0.16% |
| 2 | Federal National Mortgage Association | 0.12% | 0.12% | 0.12% |
| 3 | Federal Home Loan Mortgage Corp. | 0.11% | 0.11% | 0.11% |
| 4 | Government National Mortgage Association | 0.09% | 0.30% | 0.09% |
| 5 | Federal Home Loan Mortgage Corp. | 0.08% | 0.12% | 0.08% |
| 6 | Federal National Mortgage Association | 0.08% | 0.33% | 0.08% |
| 7 | Federal Home Loan Mortgage Corp. | 0.08% | 0.18% | 0.08% |
| 8 | Federal National Mortgage Association | 0.08% | 0.17% | 0.08% |
| 9 | Government National Mortgage Association | 0.08% | 0.41% | 0.08% |
| 10 | Government National Mortgage Association | 0.08% | 0.55% | 0.08% |
| 11 | Government National Mortgage Association | 0.07% | 0.53% | 0.07% |
| 12 | Federal National Mortgage Association | 0.07% | 0.13% | 0.07% |
Only in IUSB
16,829 total- Federal National Mortgage Association or Federal Home Loan Mortgage Corp. 0.41%
- United States of America 0.37%
- United States of America 0.37%
- United States of America 0.36%
- United States of America 0.35%
- United States of America 0.34%
- United States of America 0.34%
- United States of America 0.34%
- United States of America 0.33%
- United States of America 0.33%
Only in MBB
9,929 total- Government National Mortgage Association 0.95%
- UMBS, TBA 0.83%
- Government National Mortgage Association 0.67%
- UMBS, TBA 0.64%
- Government National Mortgage Association 0.46%
- Government National Mortgage Association 0.36%
- UMBS, TBA 0.34%
- Fannie Mae 0.33%
- Fannie Mae 0.28%
- UMBS, TBA 0.26%
Related comparisons
More comparisons with IUSB
- IUSB vs VGLT · Vanguard Long-Term Treasury Index Fund ETF Shares 7.5%
- IUSB vs CGCP · Capital Group Core Plus Income ETF 7.3%
- IUSB vs JCPB · JPMorgan Core Plus Bond ETF 7.2%
- IUSB vs VMBS · Vanguard Mortgage-Backed Securities Index Fund ETF Shares 4.7%
- IUSB vs NEAR · iShares Short Duration Bond Active ETF 4.1%
- IUSB vs TLT · iShares 20+ Year Treasury Bond ETF 4.1%
More comparisons with MBB
- MBB vs SCHZ · Schwab U.S. Aggregate Bond ETF 6.8%
- MBB vs SPAB · State Street SPDR Portfolio Aggregate Bond ETF 5.7%
- MBB vs BND · Vanguard Total Bond Market Index Fund ETF Shares 5.2%
- MBB vs FBND · Fidelity Total Bond ETF 4.8%
- MBB vs VCRB · Vanguard Core Bond ETF 3.2%
- MBB vs JCPB · JPMorgan Core Plus Bond ETF 2.3%
Percentages are holdings overlap with the named fund.
Open IUSB or MBB at a brokerage
Both funds trade commission-free at major US brokerages.
Affiliate links — opening an account through these earns PlainIndex a one-time referral. Scoring is computed before any affiliate consideration; see our methodology and funding disclosure.
Holdings overlap is the sum of min(weight_a, weight_b) over positions
matched on ISIN (CUSIP fallback). Methodology: see
/methodology/.
Comparing two funds doesn't endorse swapping one for the other. Tax-lot history, account type, and personal goals matter — PlainIndex publishes data and methodology, not investment advice.