Jensen Huang is visiting China. The Nvidia CEO is caught in a trade war. - MarketWatch

1. Nvidia CEO Jensen Huang visits China amid U.S.-China trade tensions. 2. Huang highlights China as a vital market for Nvidia's AI chips. 3. Nvidia faces a $5.5 billion financial hit due to new export regulations. 4. China contributed 13% to Nvidia's revenue last year; significant shipments likely to China. 5. Nvidia stock fell 22% this year, but rose 1% in premarket trading.