ETF Overlap

Two funds with different names can be largely the same investment. A world ETF and an S&P 500 ETF share the same handful of American technology companies at the top. Adding a technology sector fund makes the concentration worse, not better.

What we measure. For every company held by both funds we take the smaller of the two weights and add those up, then divide by the smaller of the two portfolios we have data for. The result is the share of capital that finances the same companies in both funds. We deliberately do not count how many holdings appear in both: that number sounds larger and says less, because the several hundred smallest positions of a world fund together barely move the needle.

What it does not tell you. Overlap is duplication, not risk. Two funds with no shared holding at all can still move almost identically — that is a question of correlation, not of composition. And a high overlap is not automatically a mistake: it depends on what the rest of the portfolio looks like.

Ready-made comparisons119

Highest overlap100.0%

Lowest10.0%

The Largest Duplications

Fund pairs across different indices, ranked by the share of capital financing the same companies in both.

ETF pairs by overlap
Comparison	Overlap	shared holdings
EUNL vs IUSQ	89.2%	1129
SPYI vs IUSQ	84.3%	1390
SPYM vs IS3N	83.7%	1064
ZPRG vs ZPD3	81.2%	48
SPSA vs WIMI	80.0%	1272
XDWD vs XD9U	74.9%	478
SXR8 vs SPPW	72.9%	412
SPY5 vs SPPW	72.9%	412
SPY5 vs XDWD	72.9%	412
SPY5 vs XDWL	72.9%	412
EUNL vs SXR8	72.3%	414
SPYL vs SPYY	65.7%	412
SXR8 vs IUSQ	65.1%	414
SPYL vs IUSQ	65.0%	412
SPYL vs SPYI	63.1%	467
EXXT vs XUIT	54.3%	37
EXXT vs QDVE	54.0%	34
EXXT vs XMIT	52.8%	40
WDSD vs SMC	47.2%	185
WDSD vs XXSC	47.2%	185
ZPRS vs SMC	47.2%	185
ZPRS vs XXSC	47.2%	185
EXXT vs WIMI	42.1%	96
SPYL vs QDVE	40.2%	72
SPY5 vs XUTC	40.1%	65

Data note 1

Compare Indices Instead of Funds

To find out whether two investment ideas overlap, compare the indices — the fund wrapper does not change that.