CSPX vs SPY: how much do they overlap?
iShares Core S&P 500 UCITS ETF (USD Acc) (CSPX) · SPDR S&P 500 ETF Trust (SPY)
CSPX and SPY overlap by 96.2% by portfolio weight. In practical terms, about 3.8% of the smaller-weighted exposure is different between the two funds. They share 497 stocks; the largest shared position is Nvidia Corp (NVDA), contributing 7.7% to the overlap.
overlap by weight · 497 shared holdings
CSPX: 503 holdings (as of 2026-08-04) · SPY: 504 holdings (as of 2026-08-05)
Holdings dates reflect the latest official files available for each issuer. Some issuers publish daily files; others are represented by periodic SEC filings. Analysis template updated 2026-08-05.
Note: the two funds' latest official filings have different dates, which can understate overlap slightly for funds tracking similar indexes.
High overlap
What this means
CSPX and SPY are largely the same portfolio. Holding both adds little diversification — most dollars end up in the same underlying stocks.
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.
Top shared holdings
| Company | Ticker | in CSPX | in SPY |
|---|---|---|---|
| Nvidia Corp | NVDA | 7.7% | 7.99% |
| Apple Inc | AAPL | 6.82% | 6.87% |
| Microsoft | MSFT | 5.49% | 5.45% |
| Amazon.Com Inc | AMZN | 4.08% | 4.02% |
| Alphabet Class A | GOOGL | 3.32% | 3.2% |
| Broadcom Inc | AVGO | 2.97% | 2.98% |
| Alphabet Class C | GOOG | 2.66% | 2.56% |
| Meta Platforms Class A | META | 1.94% | 1.95% |
| Micron Technology | MU | 1.51% | 1.52% |
| Jpmorgan Chase & Co | JPM | 1.44% | 1.45% |
FAQ
How much do CSPX and SPY overlap?
CSPX and SPY have a 96.2% overlap by weight, sharing 497 holdings (out of 503 in CSPX and 504 in SPY), based on official issuer holdings as of 2026-08-04.
What does 96.2% overlap mean?
CSPX and SPY are largely the same portfolio. Holding both adds little diversification — most dollars end up in the same underlying stocks.
Which stocks do CSPX and SPY both hold?
The largest shared positions are Nvidia Corp, Apple Inc, Microsoft, Amazon.Com Inc, Alphabet Class A. The full list of top shared holdings with weights in each fund is shown on this page.