Your 10% Nvidia Position Could Be Nearly 19%. Check Your Funds.

You own an S&P 500 fund, a technology ETF and a few shares of Nvidia. Three lines on the brokerage screen. Three separate investments.

But how much Nvidia do you actually own?

In the hypothetical $100,000 portfolio below, the individual stock position is 10%. Once we count the shares held inside the two funds, total Nvidia exposure rises to approximately 18.84%.

No hidden leverage. No complicated options strategy. Just the same company showing up in more than one place.

The portfolio is hypothetical. The fund weights are real, published by State Street as of September 14, 2026. This is a worked example of overlapping ownership, not a recommended allocation or a survey of what investors typically hold.

What does the portfolio look like?

We start with $60,000 in the State Street SPDR S&P 500 ETF Trust (SPY), $30,000 in the State Street Technology Select Sector SPDR ETF (XLK) and $10,000 in Nvidia shares. Those amounts represent current position values, not purchase prices.

The two funds serve different purposes. SPY tracks a broad large-company U.S. index. XLK focuses on the technology sector. Adding the second fund changes the mix of businesses you own, but it does not necessarily introduce different companies.

That is where counting tickers stops being useful.

Your 10% stock position is only part of the answer

State Street listed Nvidia at 7.78% of SPY and 13.90% of XLK in its September 14 fund holdings. These are the fund weights, not the slightly different index weights displayed on the same pages. Sources: SPY fund holdings and XLK fund holdings.

Multiply each fund position by its allocation to the company, then add the directly owned shares.

The funds add another $8,838 of exposure. That is an extra 8.838 percentage points of the whole portfolio, beyond the 10% individual position.

This does not mean the brokerage statement is wrong. It reports the investments held in the account. We are answering a different question: how much of their value traces back to one underlying company?

Why does the difference matter?

A simple sensitivity calculation makes the difference tangible. Suppose that one company’s shares fell 20%, while every other underlying holding stayed unchanged.

Looking only at the $10,000 direct position suggests a $2,000 loss, or 2% of the portfolio. Applying the same change to the full estimated exposure produces a $3,767.60 loss, or approximately 3.77% of the portfolio.

This is arithmetic, not a forecast. Real markets do not hold everything else still. Other holdings can move in either direction, and the fund weights change with them.

It does show why a position can matter more to your results than its standalone line on the screen suggests.

Overlap is measurable. “AI exposure” needs more care.

Our explanation of the September 14 AI stock selloff raised a broader question: how much of a portfolio depends on the AI infrastructure spending cycle?

This calculation answers one piece of that question. It does not answer all of it.

18.84% is estimated exposure to one company’s stock. It is not a measured percentage of the portfolio dependent on AI revenue. A company’s share price reflects multiple businesses, expectations and risks. Other holdings may depend on the same customers or spending plans without owning that company at all.

Likewise, calling the entire S&P 500 fund an AI investment would count plenty of unrelated businesses. Calling every technology company the same bet would flatten meaningful differences between suppliers, customers and competitors.

Start with the ownership you can count. Then examine the business assumptions those holdings share.

How do you check your own portfolio?

Choose the portfolio you are measuring first. If you mean all your investments, include the relevant retirement accounts and other accounts in the total. A percentage calculated from one brokerage account cannot describe everything you own.

Next, take each fund’s current dollar value and multiply it by the company’s weight in the issuer’s published holdings. Add the direct position, then divide by the total portfolio value.

Company exposure = direct position + the sum of each fund position × that company’s fund weight.

Use holdings from the same date where possible. If dates differ, record them and treat the answer as an estimate. Top-ten lists can demonstrate overlap, but a company missing from that list may still appear in the full holdings file.

Repeat for other large positions. The goal is to find out whether the concentration you have matches the concentration you intended.

The number is a question, not a sell signal

Owning the same company through several investments is not automatically a mistake. An investor may deliberately want that exposure. A diversified fund still provides exposure to its other holdings even when some names repeat.

What deserves attention is the gap between the allocation you believe you have and the one you actually hold.

If you chose this company to be 10% of your portfolio, would you have made the same decision knowing the funds brought it closer to 19%?

Sources and calculation notes

StockHitter calculations use State Street’s published SPY and XLK fund holdings dated September 14, 2026, accessed September 15. The source pages update over time; the weights used here are preserved in the tables above.

Fund weights are rounded by the issuer. Dollar exposure is estimated by applying those weights to hypothetical position values, ignoring small ETF market-price premiums or discounts to net asset value. The example assumes unleveraged holdings, no options, no short positions and no other assets in the stated portfolio. It is not a backtest, and the sensitivity example excludes trading costs and taxes. This is general educational analysis, not personalized investment advice.