IWO vs SPSM overlap - what they share and where they differ
IWO and SPSM share 39.1% of their weight across 268 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.
IWO and SPSM
39.1%
268 shared positions
IWO
iShares Russell 2000 Growth ETF
Reported positions cover 99% of the fund, 975 positions · Jun 30, 2026
Top 10: 6.1%·Holdings of IWO
SPSM
State Street(R) SPDR(R) Portfolio S&P 600(TM) Small Cap ETF
Reported positions cover 100% of the fund, 599 positions · Jun 30, 2026
Top 10: 5.9%·Holdings of SPSM
Reported positions cover IWO 99%, SPSM 100% of each fund. An overlap cannot exceed the smaller coverage, so a low figure can mean little overlap or thin reporting.
SPSM vs IWO side by side
IWOiShares Russell 2000 Growth ETF
975
stock positions reported to the SEC
56.8% of its weight is in 707 names SPSM does not hold
SPSMState Street(R) SPDR(R) Portfolio S&P 600(TM) Small Cap ETF
599
stock positions reported to the SEC
51.3% of its weight is in 331 names IWO does not hold
Where each fund's weight sits
Largest sectors for both funds
The widest gap is Financial Services: SPSM has 15.7 points more of it.
The figures side by side
| IWO | SPSM | |
|---|---|---|
| Filing date | Jun 30, 2026 | Jun 30, 2026 |
| Stock positions reported | 975 | 599 |
| Weight of the ten largest | 6.1% | 5.9% |
| Largest position | MOG.A 0.7% | FORM 0.7% |
| Held alone | 707 positions, 56.8% | 331 positions, 51.3% |
| Covered by stock positions | 99% | 100% |
Holdings they share
| Stock | In IWO | In SPSM | Counted |
|---|---|---|---|
| AGXArgan, Inc. | 0.66% | 0.60% | 0.60% |
| BTSGBrightSpring Health Services, Inc. | 0.68% | 0.60% | 0.60% |
| MXLMaxLinear, Inc. | 0.66% | 0.58% | 0.58% |
| KRYSKrystal Biotech, Inc. | 0.58% | 0.53% | 0.53% |
| ESEESCO Technologies, Inc. | 0.56% | 0.49% | 0.49% |
| GKOSGlaukos Corp. | 0.48% | 0.45% | 0.45% |
| SNEXStoneX Group, Inc. | 0.52% | 0.45% | 0.45% |
| PLXSPlexus Corp. | 0.49% | 0.44% | 0.44% |
| RHPRyman Hospitality Properties, Inc. | 0.48% | 0.44% | 0.44% |
| FSSFederal Signal Corp. | 0.47% | 0.43% | 0.43% |
What each holds alone
The heaviest positions one fund reports and the other does not.
Only in IWO
Only in SPSM
Questions people ask
Is IWO the same as SPSM?
39.1% of their weight sits in the same 268 holdings. IWO also reports MOG.A, FROG, COMP, which the other does not. SPSM also reports FORM, VSAT, MOH, which the other does not.
How is the overlap between IWO and SPSM measured?
For every stock both funds report, the smaller of the two weights counts, and the sum is the overlap. The reported positions cover 99% of IWO and 100% of SPSM, so the number cannot exceed the smaller coverage.
Which holds more, SPSM or IWO?
IWO reports 975 stock positions and SPSM reports 599. 56.8% of IWO's weight sits in names SPSM does not hold, and 51.3% of SPSM's weight in names IWO does not hold. The ten largest positions are 6.1% of IWO and 5.9% of SPSM.
How do IWO and SPSM differ by sector?
The widest gap is Financial Services: SPSM has 15.7 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
SPSM 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.