QQQ and SPY overlap: shared ETF holdings explained

Two fund names are not a diversification measurement

When you hold QQQ and SPY, the useful question is how their underlying holdings combine in your portfolio. Start from each issuer's holdings list and use a common observation date. This guide does not state a current overlap percentage: holdings and weights change, and an undated number would obscure that dependence. Instead, we show the calculation with fictional companies so you can repeat it using the data you actually have.

Count shared holdings, then consider their weights

The number of shared securities tells you how many names appear in both lists. Weighted overlap asks a different question: how much of the two allocations can be matched security by security? For each common holding, take the smaller of its two percentage weights and add those smaller weights. In notation, overlap = sum of min(weight in A, weight in B). This definition assumes comparable, complete, long-only holdings lists measured on the same basis. It is not a prediction of future price correlation.

A fictional example you can check

Suppose Fund A holds ALPHA at 40% and BETA at 60%. Fund B holds ALPHA at 25% and GAMMA at 75%. There is one shared name, ALPHA. The matched weight is min(40%, 25%) = 25%, so weighted overlap is 25%. BETA and GAMMA contribute zero because each appears in only one list. These are invented fund allocations for demonstrating arithmetic, not the actual holdings of QQQ, SPY or any other fund.

Your combined exposure is another calculation

Now suppose half of your portfolio is in fictional Fund A and half is in Fund B. Your ALPHA exposure is 0.5 × 40% + 0.5 × 25% = 32.5%. BETA contributes 30% and GAMMA 37.5%, adding to 100%. If you also own ALPHA directly, include that holding and recalculate every allocation using the full portfolio total. This is why an overlap percentage between two funds cannot by itself describe the concentration of a particular person's portfolio.

Check what the input leaves out

A top-ten list is a partial view. Two such lists can miss overlap further down the holdings and must not be labeled complete fund overlap. Also check whether the weights include cash, derivatives or holdings reported in different units. Match share classes and security identifiers deliberately rather than assuming similar names are identical. If you only have partial data, show the observed portion and its coverage; do not quietly scale the visible positions to 100% and present that as the whole fund.

Sources: Invesco: QQQ fund information and holdings · State Street: SPY fund information and holdings

Turn the result into a better question

Use the calculation to ask where exposures accumulate: one company, a sector or a particular business theme. Whether that concentration is suitable depends on the investor's circumstances; the arithmetic does not settle that question. In GSDAQ, use your holdings as context for reviewing company and market information. Keep the issuer files and their dates with your calculation so you can distinguish a real holdings change from a change in data coverage the next time you compare.

Sources

• Invesco: QQQ fund information and holdings
• State Street: SPY fund information and holdings