ISTB vs AGG: Holdings Overlap
ISTBiShares Core 1-5 Year USD Bond ETF
iShares · 7059 holdings · $5.1B · as of 2026-04-30
AGGiShares Core U.S. Aggregate Bond ETF
iShares · 13266 holdings · $137.7B · as of 2026-05-31
Holdings snapshots are 31 days apart (ISTB: 2026-04-30, AGG: 2026-05-31). Weights and index membership change between snapshots, so the true current overlap is typically higher than shown. For funds tracking the same index, the gap can be 5–15 points.
How similar are ISTB and AGG?
iShares Core 1-5 Year USD Bond ETF (ISTB, by iShares) holds 7059 positions; iShares Core U.S. Aggregate Bond ETF (AGG, by iShares) holds 13266. They have 3690 holdings in common, and by portfolio weight the two funds are 33.5% identical. In practical terms the pair is moderately overlapping; they share a meaningful core, but each fund adds distinct exposure.
- Overlap by Weight
- 33.5%Sum of the smaller weight of each shared holding
- Shared Holdings
- 3690ISTB holds 7059 · AGG holds 13266
- Weight in Shared Holdings
- ISTB 77%·AGG 35%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 ISTB
3369 of 7059 positions (21.1% of the fund) are not held by AGG. Showing the top 30 by weight.
- U.S. Treasury Notes0.73%
- U.S. Treasury Notes0.45%
- Uniform Mortgage-Backed Security, TBA0.20%
- U.S. Treasury Notes0.15%
- Freddie Mac Pool0.13%
- Argentina Republic Government International Bonds0.11%
Only in AGG
9576 of 13266 positions (63.1% of the fund) are not held by ISTB. Showing the top 30 by weight.
- U.S. Treasury Notes0.42%
- U.S. Treasury Notes0.41%
- U.S. Treasury Notes0.40%
- U.S. Treasury Notes0.40%
- U.S. Treasury Notes0.39%
- U.S. Treasury Notes0.39%
Performance
| Fund | 1M | YTD | 1Y | 3Y (ann.) | 5Y (ann.) | 10Y (ann.) | Yield |
|---|---|---|---|---|---|---|---|
| ISTB | +0.3% | +1.0% | +3.0% | +5.0% | +1.9% | +2.3% | 4.27% |
| AGG | -0.3% | +0.0% | +2.4% | +4.2% | -0.2% | +1.4% | 4.04% |
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 ISTB vs AGG →
Shared Holdings(3690)
The top 10 shared positions account for 9% of the overlap, led by U.S. Treasury Notes, U.S. Treasury Notes and U.S. Treasury Notes.
| U.S. Treasury Notes | 0.99% | 0.41% | 0.41% |
|---|---|---|---|
| U.S. Treasury Notes | 0.86% | 0.33% | 0.33% |
| U.S. Treasury Notes | 0.46% | 0.31% | 0.31% |
| U.S. Treasury Notes | 0.67% | 0.31% | 0.31% |
| U.S. Treasury Notes | 0.46% | 0.30% | 0.30% |
| U.S. Treasury Notes | 0.83% | 0.30% | 0.30% |
| U.S. Treasury Notes | 0.67% | 0.29% | 0.29% |
| U.S. Treasury Notes | 0.98% | 0.29% | 0.29% |
| U.S. Treasury Notes | 0.96% | 0.28% | 0.28% |
| U.S. Treasury Notes | 0.91% | 0.27% | 0.27% |
| U.S. Treasury Notes | 0.89% | 0.26% | 0.26% |
| U.S. Treasury Notes | 0.26% | 0.31% | 0.26% |
| U.S. Treasury Notes | 0.26% | 0.35% | 0.26% |
| U.S. Treasury Notes | 0.62% | 0.25% | 0.25% |
| U.S. Treasury Notes | 0.34% | 0.25% | 0.25% |
| U.S. Treasury Notes | 0.60% | 0.24% | 0.24% |
| U.S. Treasury Notes | 0.56% | 0.24% | 0.24% |
| U.S. Treasury Notes | 0.25% | 0.24% | 0.24% |
| U.S. Treasury Notes | 0.50% | 0.24% | 0.24% |
| U.S. Treasury Notes | 0.26% | 0.24% | 0.24% |
| U.S. Treasury Notes | 0.68% | 0.24% | 0.24% |
| U.S. Treasury Notes | 0.59% | 0.23% | 0.23% |
| U.S. Treasury Notes | 0.70% | 0.23% | 0.23% |
| U.S. Treasury Notes | 0.55% | 0.23% | 0.23% |
| U.S. Treasury Notes | 0.55% | 0.23% | 0.23% |
Showing the top 250 of 3690 shared holdings by overlap weight.
Frequently Asked Questions
How much do ISTB and AGG overlap?
ISTB and AGG overlap by 33.5% of portfolio weight. They share 3690 holdings (ISTB holds 7059 positions and AGG holds 13266), based on each fund's latest SEC-reported holdings.
Is it redundant to own both ISTB and AGG?
The two portfolios are 33.5% identical by weight. Owning both is defensible: they share a meaningful core, but each fund adds exposure the other lacks.
What are the biggest shared holdings of ISTB and AGG?
The largest positions held by both funds are U.S. Treasury Notes, U.S. Treasury Notes, U.S. Treasury Notes, U.S. Treasury Notes and U.S. Treasury Notes. Together the top 10 shared positions account for 9% of the total overlap.
What does ISTB own that AGG doesn't?
3369 positions (21.1% of ISTB) are unique to ISTB, led by U.S. Treasury Notes, U.S. Treasury Notes and Uniform Mortgage-Backed Security, TBA. In the other direction, 9576 positions (63.1% of AGG) are unique to AGG.