ETF and Mutual Fund Analysis

Holdings as of August 12, 2026 (SPY) and March 31, 2026 (VIIIX)

ETF and Mutual Fund Analysis

Overlap, Comparison, and Diversification for Your Portfolio

Home > Compare > SPY vs VIIIX Holdings as of August 12, 2026 (SPY) and March 31, 2026 (VIIIX)

SPY vs VIIIX: Portfolio Overlap

SPDR® S&P 500® ETF Trust vs Vanguard Institutional Index Fund

91.3%
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.

SPY
505 equity holdings
as of August 12, 2026
VIIIX
503 equity holdings
as of March 31, 2026
491 stocks held in common
Overlap View Venn Diagram
91.3% OVERLAP SPY VIIIX
Overlapping Holdings
10 Top 10 of 491 shared, by overlap contribution
# Stock SPY VIIIX Overlap%
1
NVDA
 8.14% 7.60% 7.60%
2
AAPL
 6.66% 6.68% 6.66%
3
MSFT
 5.49% 4.93% 4.93%
4
AMZN
 3.92% 3.65% 3.65%
5
GOOGL
 3.02% 3.00% 3.00%
6
AVGO
 2.95% 2.63% 2.63%
7
GOOG
 2.43% 2.40% 2.40%
8
META
 1.91% 2.24% 1.91%
9
BRK.B
 1.40% 1.57% 1.40%
10
TSLA
 1.38% 1.87% 1.38%
Most Divergent Holdings Stocks held by one fund but absent from the other
Only in SPY — SPDR® S&P 500® ETF Trust
StockWeight
XOM0.99%
MRVL0.29%
HON0.11%
HONA0.08%
US DOLLAR0.08%
Only in VIIIX — VANGUARD INSTITUTIONAL INDEX FUND
StockWeight
XOM1.27%
HON0.26%
EA0.08%
CTRA0.05%
CCL0.05%

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

SPY (SPDR® S&P 500® ETF Trust) and VIIIX (Vanguard Institutional Index Fund) share 91.3% portfolio overlap as of SPY's August 12, 2026 filing and VIIIX's March 31, 2026 filing, across 491 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 SPY 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 SPY 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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