Boeing has sold 900 aircraft to China since 1972, with thousands more potential orders expected as the country adds airports -- and travelers. GM has seen China vehicle sales overtake U.S. sales. It's planning to build a third joint-venture factory in the country to serve expected growth in light commercial vehicles. Falling share prices are one thing. Monetary tightening could also hit the Chinese partners of these U.S. companies if they're looking for loans to expand. "As Chinese firms are usually the major suppliers to North American companies, their level of activity is often interpreted to correlate with the level of demand coming from New York-based firms," warns Wojtek Zarzycki, chief investment officer with Optimal Investing in Canada. At the time of publication the author had no position in any of the stocks mentioned.Ralph Jennings is on LinkedIn.This article was written by an independent contributor, separate from TheStreet's regular news coverage.