CSPX vs SPY ETF holdings comparison
iShares Core S&P 500 UCITS ETF (USD Acc) (CSPX) · SPDR S&P 500 ETF Trust (SPY)
CSPX and SPY overlap by 95.3% by portfolio weight. The remaining 4.7 percentage points are not counted as shared holdings weight by this calculation. They share 494 stocks; the largest shared position is Nvidia (NVDA), contributing 8.07% to the overlap.
The holdings dates differ. This can slightly understate overlap for funds tracking similar indexes.
What this means
CSPX and SPY share most of their portfolio weight in the same underlying stocks. OverlapCheck labels this "high holdings overlap" using house ranges of 70% or more, 30% to under 70%, and under 30%. These descriptive ranges are not industry standards or investment guidance. Holdings overlap does not measure correlation, volatility, geographic or factor exposure, fees, or suitability.
Overlap by weight sums the smaller of the two funds' weights for every stock they both hold. It answers "how much of my money is in the same stocks either way?" See methodology.
This comparison covers normalized equity positions represented in the dataset. Cash, derivatives, options, structured notes, and other non-equity assets are not included, so the result is not a complete comparison of every asset or risk in either fund.
Top shared holdings
| Company | Ticker | in CSPX | in SPY |
|---|---|---|---|
| Nvidia | NVDA | 8.07% | 8.22% |
| Apple | AAPL | 7.02% | 7.39% |
| Microsoft | MSFT | 5.69% | 5.57% |
| Amazon.Com Inc | AMZN | 3.84% | 3.79% |
| Alphabet Class A | GOOGL | 3.00% | 3.11% |
| Broadcom Inc | AVGO | 2.65% | 2.58% |
| Alphabet Class C | GOOG | 2.39% | 2.49% |
| Meta Platforms Class A | META | 1.90% | 2.44% |
| Micron Technology | MU | 1.63% | 1.76% |
| Tesla Inc | TSLA | 1.56% | 1.58% |
Holdings only in CSPX or SPY
CSPX has 9 fund-only positions representing approximately 1.6 percentage points of reported exposure; SPY has 9 fund-only positions representing approximately 1.8 percentage points of reported exposure. These are positions whose normalized security identifiers appear in one issuer file but not the other.
Largest positions only in CSPX
| Company | Ticker | Weight |
|---|---|---|
| Berkshire Hathaway Inc Class B | BRKB | 1.39% |
| Oneok | OKE | 0.09% |
| Vivmark Residential | VMRK | 0.07% |
| Keycorp | KEY | 0.03% |
| Alexandria Real Estate Equities Re | ARE | 0.01% |
| Builders Firstsource Inc | BLDR | 0.01% |
| Molson Coors Brewing Class B | TAP | 0.01% |
| Trade Desk Inc Class A | TTD | 0.01% |
| Brown Forman Class B | BFB | 0.01% |
Largest positions only in SPY
| Company | Ticker | Weight |
|---|---|---|
| Berkshire Hathaway Inc Cl B | BRK.B | 1.40% |
| Bloom Energy Corp A | BE | 0.12% |
| Oneok Inc | OKE | 0.09% |
| Vivmark Residential | VMRK | 0.07% |
| Everpure Inc A | P | 0.06% |
| Illumina Inc | ILMN | 0.05% |
| Keycorp | KEY | 0.03% |
| Alexandria Real Estate Equit | ARE | 0.01% |
| Brown Forman Corp Class B | BF.B | <0.01% |
FAQ
How much do CSPX and SPY overlap?
CSPX and SPY have 95.3% overlap by weight, sharing 494 equity positions (out of 503 in CSPX and 503 in SPY). The official holdings files used are dated 2026-08-31 for CSPX and 2026-09-21 for SPY.
What does 95.3% overlap mean?
CSPX and SPY share most of their portfolio weight in the same underlying stocks. OverlapCheck labels this "high holdings overlap" using house ranges of 70% or more, 30% to under 70%, and under 30%. These descriptive ranges are not industry standards or investment guidance. Holdings overlap does not measure correlation, volatility, geographic or factor exposure, fees, or suitability.
Which stocks do CSPX and SPY both hold?
The largest shared positions are Nvidia, Apple, Microsoft, Amazon.Com Inc, Alphabet Class A. The top shared holdings with weights in each fund are shown on this page.
What holdings are different between CSPX and SPY?
CSPX has 9 positions not found in SPY, while SPY has 9 positions not found in CSPX. The largest fund-only positions and their weights are shown on this page.
Related comparisons
One side of this pair is a UCITS ETF. How share classes and listings map to one fund, and which popular UCITS combinations repeat the same US mega-caps, is covered in ETF overlap for European investors.