IWM vs SPSM overlap - what they share and where they differ
IWM and SPSM share 45.2% of their weight across 519 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.
IWM and SPSM
45.2%
519 shared positions
IWM
iShares Russell 2000 ETF
Reported positions cover 100% of the fund, 1,785 positions · Jun 30, 2026
Top 10: 3.4%·Holdings of IWM
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 IWM 100%, 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 IWM side by side
IWMiShares Russell 2000 ETF
1,785
stock positions reported to the SEC
54.6% of its weight is in 1,266 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
20.8% of its weight is in 80 names IWM does not hold
Where each fund's weight sits
Largest sectors for both funds
The widest gap is Consumer Cyclical: SPSM has 11.3 points more of it.
The figures side by side
| IWM | SPSM | |
|---|---|---|
| Filing date | Jun 30, 2026 | Jun 30, 2026 |
| Stock positions reported | 1,785 | 599 |
| Weight of the ten largest | 3.4% | 5.9% |
| Largest position | MOG.A 0.4% | FORM 0.7% |
| Held alone | 1,266 positions, 54.6% | 80 positions, 20.8% |
| Covered by stock positions | 100% | 100% |
Holdings they share
| Stock | In IWM | In SPSM | Counted |
|---|---|---|---|
| BTSGBrightSpring Health Services, Inc. | 0.35% | 0.60% | 0.35% |
| VSATViasat, Inc. | 0.35% | 0.66% | 0.35% |
| AGXArgan, Inc. | 0.34% | 0.60% | 0.34% |
| MXLMaxLinear, Inc. | 0.34% | 0.58% | 0.34% |
| KRYSKrystal Biotech, Inc. | 0.30% | 0.53% | 0.30% |
| ESEESCO Technologies, Inc. | 0.29% | 0.49% | 0.29% |
| ALKSAlkermes plc | 0.27% | 0.47% | 0.27% |
| SNEXStoneX Group, Inc. | 0.27% | 0.45% | 0.27% |
| GKOSGlaukos Corp. | 0.25% | 0.45% | 0.25% |
| NPOEnpro, Inc. | 0.25% | 0.43% | 0.25% |
What each holds alone
The heaviest positions one fund reports and the other does not.
Only in IWM
Only in SPSM
Questions people ask
Is IWM the same as SPSM?
45.2% of their weight sits in the same 519 holdings. IWM also reports MOG.A, HUT, CYTK, which the other does not. SPSM also reports FORM, MOH, ESI, which the other does not.
How is the overlap between IWM 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 100% of IWM and 100% of SPSM, so the number cannot exceed the smaller coverage.
Which holds more, SPSM or IWM?
IWM reports 1,785 stock positions and SPSM reports 599. 54.6% of IWM's weight sits in names SPSM does not hold, and 20.8% of SPSM's weight in names IWM does not hold. The ten largest positions are 3.4% of IWM and 5.9% of SPSM.
How do IWM and SPSM differ by sector?
The widest gap is Consumer Cyclical: SPSM has 11.3 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.