Big China trouble in your little portfolio?

Key Points

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A cleaner works in front of a Goodyear retail shop in Beijing.
Alexander F. Yuan | AP

Investors continue to hold onto the notion that China's stock market slide won't affect U.S. equities, bidding the S&P 500 to near a record high last week despite the Asian market's troubles over the past one month.

One reason cited is the relatively closed nature of the Shanghai stock market.

More frequently, investors say the local crash in equities won't trickle over to the Chinese economy, a market many U.S. companies depend on for their only source of revenue growth.

But when Ray Dalio, the largest hedge fund manager in the world, changes his mind about that theory, you may need to reassess as well.

CNBC Pro looked at several ways to find any China time bombs lurking in your portfolio.

First, we ran analysis using quantitative tool Kensho to find out which S&P 500 shares get slammed when Chinese stocks sell off.

We looked at what happens when the iShares China Large-Cap ETF drops more than 10 percent in five days. Below are the stocks with the biggest average decline during that week.

If you need proof that these stocks are beholden to China consider that even though the stock market didn't start to crack until the final 15 days of the second quarter, many of these companies above warned about Chinese sales possibly falling short on post-earnings report conference calls.

On Freeport-McMoran's last quarterly conference call, management of the copper producer said:

"The slowdown in the China economy is a factor and the carry-on effects of the drop in stock prices in China and the impact on financial investors is certainly being shown in the copper price."

A Goodyear Tire & Rubber executive said during its latest call:

"While we see slower growth for the region in the short term versus our original expectations, we continue to view China and the rest of the region as a key long-term growth opportunity. We are investing in our teams, our products and our capabilities to drive that growth."

A search of Alcoa's conference call via FactSet shows that "China" was discussed 17 times.

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Another way we sought to find the U.S. companies with the most riding on China is a simple search of Asian sales exposure via S&P Dow Jones Indices.

Qualcomm, Applied Materials and Texas Instruments top the lists of whose Asia sales make up the greatest portion of total sales, according to S&P Dow Jones Indices. (Most companies don't disclose sales solely to China so Asia sales are used here.)

On Qualcomm's earnings call last week, "China" was uttered 28 times, according to FactSet.

Note that of the 25 S&P 500 companies with the most sales in Asia, just two have share prices that are higher in the last month.

So the overall market may be shaking China off as and Netflix shoot higher after earnings.

But outside the domestic plays, it appears trouble is brewing.

Disclosure: NBCUniversal, parent of CNBC, is a minority investor in Kensho.

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