IWB vs SPY overlap - what they share and where they differ
IWB and SPY share 86.6% of their weight across 464 common positions, read from what each fund reported to the SEC.
Each week Ploutos reads the reported positions of the largest US equity ETFs and measures, pair by pair, the weight they share: for every stock both funds hold, the smaller of the two weights counts. Two funds tracking the same index land near 100%. A sector fund inside a broad index fund lands at roughly that sector's weight.
IWB and SPY
86.6%
464 shared positions
IWB
iShares Russell 1000 ETF
Reported positions cover 100% of the fund, 946 positions · Jun 30, 2026
Top 10: 34.8%·Holdings of IWB
SPY
SPY
Reported positions cover 100% of the fund, 499 positions · Jun 30, 2026
Top 10: 37.9%·Holdings of SPY
Reported positions cover IWB 100%, SPY 100% of each fund. An overlap cannot exceed the smaller coverage, so a low figure can mean little overlap or thin reporting.
SPY vs IWB side by side
IWBiShares Russell 1000 ETF
946
stock positions reported to the SEC
13.4% of its weight is in 482 names SPY does not hold
SPY
499
stock positions reported to the SEC
6.2% of its weight is in 35 names IWB does not hold
Where each fund's weight sits
Largest sectors for both funds
The widest gap is Technology: SPY has 2.2 points more of it.
The figures side by side
| IWB | SPY | |
|---|---|---|
| Filing date | Jun 30, 2026 | Jun 30, 2026 |
| Stock positions reported | 946 | 499 |
| Weight of the ten largest | 34.8% | 37.9% |
| Largest position | NVDA 6.7% | NVDA 7.5% |
| Held alone | 482 positions, 13.4% | 35 positions, 6.2% |
| Covered by stock positions | 100% | 100% |
Holdings they share
| Stock | In IWB | In SPY | Counted |
|---|---|---|---|
| NVDANVIDIA CORPORATION | 6.72% | 7.52% | 6.72% |
| AAPLAPPLE INC. | 6.03% | 6.59% | 6.03% |
| GOOGLALPHABET INC. | 5.42% | 5.84% | 5.42% |
| MSFTMICROSOFT CORPORATION | 3.99% | 4.30% | 3.99% |
| AMZNAMAZON.COM, INC. | 3.33% | 3.62% | 3.33% |
| AVGOBROADCOM INC. | 2.53% | 2.77% | 2.53% |
| MUMICRON TECHNOLOGY, INC. | 1.87% | 2.02% | 1.87% |
| METAMETA PLATFORMS, INC. | 1.78% | 1.92% | 1.78% |
| TSLATESLA, INC. | 1.77% | 1.84% | 1.77% |
| LLYELI LILLY AND COMPANY | 1.38% | 1.47% | 1.38% |
What each holds alone
The heaviest positions one fund reports and the other does not.
Only in IWB
Only in SPY
Questions people ask
Is IWB the same as SPY?
86.6% of their weight sits in the same 464 holdings. IWB also reports JPMORGAN CHASE & CO., EXXON MOBIL CORPORATION, GENERAL ELECTRIC COMPANY, which the other does not. SPY also reports JPMORGAN CHASE & CO, EXXON MOBIL CORP, GENERAL ELECTRIC CO, which the other does not.
How is the overlap between IWB and SPY measured?
For every stock both funds report, the smaller of the two weights counts, and the sum is the overlap. The reported positions cover 100% of IWB and 100% of SPY, so the number cannot exceed the smaller coverage.
Which holds more, SPY or IWB?
IWB reports 946 stock positions and SPY reports 499. 13.4% of IWB's weight sits in names SPY does not hold, and 6.2% of SPY's weight in names IWB does not hold. The ten largest positions are 34.8% of IWB and 37.9% of SPY.
How do IWB and SPY differ by sector?
The widest gap is Technology: SPY has 2.2 points more of it. Sectors come from each holding's SIC code in its SEC record, summed by the weight the fund reports.
Where do the numbers come from?
From each fund's own N-PORT filing to the SEC, which lists every position and its weight. The comparison uses every equity position the fund reports; cash, futures and bonds are not counted, which is why a coverage figure sits next to every result. Holdings change between filings.
Other pairs with these funds
IWB against other funds in the table
SPY against other funds in the table
Add a third fund in the tool·All fund pairs
Descriptive data from public SEC filings. Nothing on this page is a recommendation to buy, sell or hold any fund or stock, and holdings change between filings.