ETF comparison · UCITS vs US-domiciled
CSPX vs SPY: overlap by weight, TER & holdings
iShares Core S&P 500 UCITS ETF USD (Acc) vs SPDR S&P 500 ETF Trust
Same index, different wrappers. The real comparison is not the fee, it is domicile: withholding tax on dividends, US estate-tax exposure and broker access differ far more than the holdings do.
CSPX also trades as SXR8 (Xetra), CSP1 (LSE (GBP)).
CSPX vs SPY at a glance
| CSPX | SPY | |
|---|---|---|
| Fund | iShares Core S&P 500 UCITS ETF USD (Acc) | SPDR S&P 500 ETF Trust |
| ISIN | IE00B5BMR087 | US78462F1030 |
| Index | S&P 500 | S&P 500 |
| Market exposure | US large cap | US large cap |
| TER | 0.07% | 0.09% |
| Holdings in fund | 505 | 504 |
| Fund size | ≈ 110 bn USD | ≈ 795 bn USD |
| Domicile | Ireland | the United States |
| Replication | Physical (full) | Physical (full, unit trust) |
| Use of income | Accumulating | Distributing |
| Launched | May 19, 2010 | Jan 22, 1993 |
Top shared holdings
| CSPX | SPY | |
|---|---|---|
| NVDANVIDIA | 7.85% | 8.07% |
| AAPLAPPLE | 7.44% | 7.52% |
| MSFTMICROSOFT | 5.64% | 5.62% |
| AMZNAMAZON.COM INC | 3.72% | 3.74% |
| GOOGLALPHABET CLASS A | 3.09% | 3.09% |
| GOOGALPHABET CLASS C | 2.47% | 2.47% |
| AVGOBROADCOM INC | 2.45% | 2.5% |
| METAMETA PLATFORMS CLASS A | 2.25% | 2.28% |
| MUMICRON TECHNOLOGY | 1.6% | 1.67% |
| TSLATESLA INC | 1.53% | 1.57% |
| JPMJPMORGAN CHASE & CO | 1.44% | 1.42% |
| LLYELI LILLY | 1.37% | 1.38% |
| AMDADVANCED MICRO DEVICES | 1.26% | 1.35% |
| XOMEXXONMOBIL HOLDINGS CORP | 1.07% | 1.03% |
| JNJJOHNSON & JOHNSON | 0.98% | 0.99% |
Weights per fund, normalized. 501 companies appear in both funds.
What the fee gap costs
Growth of 10,000 invested at 7% annual return, after each fund’s TER: 0.07% for CSPX, 0.09% for SPY.
| CSPX | SPY | Difference | |
|---|---|---|---|
| After 10 years | 19,543 | 19,498 | 45 |
| After 20 years | 38,194 | 38,019 | 175 |
| After 30 years | 74,643 | 74,131 | 511 |
CSPX comes out ahead by about 511 per 10,000 invested over 30 years. TER only. Trading spreads, taxes and broker fees are not included.
Domicile and withholding tax
CSPX is Irish-domiciled: the fund pays 15% US withholding on dividends under the US-Ireland treaty and accumulates the rest. SPY is US-domiciled: a non-US holder typically faces 15-30% withholding on distributions depending on their tax treaty, plus potential US estate-tax exposure above 60,000 USD. For most European investors the Irish wrapper is the safer default.
Frequently asked questions
Do CSPX and SPY overlap?+
Yes: 97.05% by weight, with 501 holdings appearing in both funds. 98.26% of CSPX’s weight is also inside SPY.
Do CSPX and SPY track the same index?+
Yes. Both funds track the same index: S&P 500. Return differences come from fees, replication and trading costs, not from index choice.
Which is cheaper, CSPX or SPY?+
CSPX: 0.07% per year against 0.09% for SPY. At 7% growth that gap is worth about 511 per 10,000 invested over 30 years.
Is it worth holding both CSPX and SPY?+
Holding both mostly duplicates exposure: 97.05% of the pair overlaps by weight. Most investors pick one, or combine one of them with a fund covering different markets.
More comparisons
Methodology
Overlap is the sum of min(weight A, weight B) across holdings that appear in both funds, with each fund’s stored weights normalized to 100%. Holdings come from issuer feeds and regulatory filings in our ETF holdings database; TER and fund size come from fund profile data and are refreshed regularly. Figures update when the underlying holdings data updates.
Holdings data as of Sep 21, 2026, from our ETF holdings database.