Nvidia (NASDAQ:NVDA) stock is down more than 3% today after the U.S. officially launched an investigation into the company following complaints from competitors that it abused its position within the artificial intelligence (AI) chip market, of which it currently controls about 80%.The U.S. Department of Justice (DOJ) is also investigating accusations that Nvidia charges its customers a steeper price for networking equipment if they plan on purchasing semiconductors from rival chipmakers Advanced Micro Devi ...