The top 20 US stock transactions: Tesla's stock price fell 6.5% due to fatal car accident investigation. Tesla, ranked third, closed down 6.55% with a transaction of $18.43 billion. The National Highway Traffic Safety Administration of the United States announced on July 31st that it will investigate a fatal Tesla car collision in Seattle in April of this year. The Washington State Department of Transportation confirmed through investigation that the vehicle involved in the accident was operating in "fully autonomous driving" mode at the time of the incident. This is at least the second fatal accident involving Tesla's assisted driving technology in two years. In addition, Republican presidential candidate Trump stated on Wednesday that although Tesla CEO Elon Musk supports him, he opposes everyone owning an electric car.