The U.S. and China have a combined annual GDP of roughly $30 trillion, according to the IMF and as Chinese President Xi Jinping pointed out, the business interests of the two countries are becoming increasingly intertwined. So which are the companies we should be watching? Boeing (BA) was graced with a visit from the Chinese Premier during his first U.S. state visit underscoring the mutually beneficial relationship between the two. The company landed $38 billion worth of manufacturing orders from China and has invested in a state of the art factory, its biggest industrial expansion on foreign soil. Boeing has estimated potential sales to China worth around $950 billion over the next two decades. Apple (AAPL) has seen its Chinese revenue spike, taking advantage of China's demand for the latest smart phones and grabbing market share from local competitors such as Xiaomi and Huawei. Greater China currently provides around 20 percent of Apple's revenue, helping to boost slowing iPhone sales in Western nations. Thanks to Chinese consumers, Apple sold a record breaking 13 million iPhone 6S and 6S Plus models across the first three days of release. Wynn Resorts (WYNN) generated 70 percent of its revenue in China last year so it has felt the results of the Chinese slowdown and the government's corruption crackdown very acutely.