The US stocks with a very real China problem

Kai Pfaffenbach | Reuters

As a China economic slowdown—the central worry of plummeting global markets for a month—finally gets confirmed by hard data, there are some U.S. stocks you simply don't want in your portfolio.

These are not the names that are subject to the "sell everything," risk-off posture occurring, but rather, the companies whose livelihoods depend on a China economy remaining in a growth mode.

Two surveys of manufacturing in China on Tuesday pointed to a contracting economy. One of those—the Caixin/Markit manufacturing purchasing managers' index—posted its lowest reading since March 2009. Meanwhile, numbers out of Macau showed gambling revenue for the country's casino capital dropped a stunning 36 percent in August from a year ago.

So CNBC Pro canvassed Wall Street research, annual reports and other sources to create the definitive list of U.S. companies with the most to lose if more weak data continue to flow out of China.

The list above is of the U.S. companies that get more than 20 percent of their revenue from China specifically. Actual data from annual reports are used if possible, but if the company does not disclose, we relied on estimated figures from Citigroup or Goldman Sachs analysts.

"Investors should be aware that management teams have not necessarily blessed the numbers as several view country data as being closely guarded strategic competitive information," said Tobias Levkovich of Citigroup in a report last week on the firm's data. "Nonetheless, it is important for the investment community to have some sense of exposure and that was the primary motivation for getting this information out, especially given even greater concern about China in terms of market performance trends recently."

Goldman agrees and has been telling clients repeatedly since mid-July to get out of the stocks estimated by the firm to be the most exposed to China.

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Many of these equities over the last month have lost significant value as the Chinese stock market crashed. Therefore, the list may be most useful by looking at the stocks that are beholden to China, but haven't yet responded to the downside.

Exposed stocks such as Avago, Nu Skin Enterprises and Intel are beating the S&P 500 over the last month.

The technology sector overall may be the one to avoid if the China-focused volatility in U.S. markets continues.

Goldman estimates the tech category of the S&P 500 gets a fifth of its sales from China. This is also why 86 members of the tech-heavy Nasdaq 100 ETF—the QQQs— are in correction territory from their 52-week high already.

But many of the stocks on the list which are already down big over the last month may still have room to fall further as the data come out and confirm investors' worst fears.

Despite being down more than 25 percent in August on concern about China exposure, Wynn fell another 4 percent Tuesday after the release of the poor Macau data.

So it may be awhile before one should start looking to these names for a value opportunity.

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