ETF and Mutual Fund Analysis

Holdings as of March 31, 2026

ETF and Mutual Fund Analysis

Overlap, Comparison, and Diversification for Your Portfolio

Home > Compare > SPYM vs VIIIX Holdings as of March 31, 2026

SPYM vs VIIIX: Portfolio Overlap

State Street(R) SPDR(R) Portfolio S&P 500(R) ETF vs Vanguard Institutional Index Fund

97.0%
Weighted portfolio overlap
Very High Overlap

The two portfolios are structurally near-identical: most of the weight sits in the same stocks, so holding both concentrates rather than spreads capital. The tier describes what the data shows, not what to do about it.

SPYM
503 equity holdings
as of March 31, 2026
VIIIX
503 equity holdings
as of March 31, 2026
476 stocks held in common
Overlap View Venn Diagram
97.0% OVERLAP SPYM VIIIX
Overlapping Holdings
10 Top 10 of 476 shared, by overlap contribution
# Stock SPYM VIIIX Overlap%
1
NVDA
 7.58% 7.60% 7.58%
2
AAPL
 6.67% 6.68% 6.67%
3
MSFT
 4.92% 4.93% 4.92%
4
AMZN
 3.64% 3.65% 3.64%
5
GOOGL
 3.00% 3.00% 3.00%
6
AVGO
 2.63% 2.63% 2.63%
7
GOOG
 2.40% 2.40% 2.40%
8
META
 2.24% 2.24% 2.24%
9
TSLA
 1.87% 1.87% 1.87%
10
BRK.B
 1.57% 1.57% 1.57%
Most Divergent Holdings Stocks held by one fund but absent from the other
Only in SPYM — State Street(R) SPDR(R) Portfolio S&P 500(R) ETF
StockWeight
Linde PLC0.41%
Eaton Corp PLC0.25%
Accenture PLC0.22%
Chubb Ltd0.21%
Medtronic PLC0.20%
Only in VIIIX — VANGUARD INSTITUTIONAL INDEX FUND
StockWeight
LIN0.41%
ETN0.25%
ACN0.22%
CB0.21%
MDT0.20%

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Frequently Asked Questions (FAQs)
What is the portfolio overlap between SPYM and VIIIX?

SPYM (State Street(R) SPDR(R) Portfolio S&P 500(R) ETF) and VIIIX (Vanguard Institutional Index Fund) share 97.0% portfolio overlap as of their March 31, 2026 filings, across 476 common stocks. Overlap is the sum of the smaller weight of each shared stock, so it reads as the share of a dollar that lands on the same companies in both funds.

Do SPYM and VIIIX invest in the same stocks?

Almost entirely. These funds hold nearly identical portfolios and offer little differentiation between them.

What are the top stocks held by both SPYM and VIIIX?

The most prominent shared holdings (by combined weight) are: NVDA, AAPL, MSFT. See the full common-holdings table on this page for weights in each fund.

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