Amazon stock is on track to finish this week higher than it started — breaking its longest weekly losing streak since 2008.

"Our customers, shareholders, and business will be well-served by our investing aggressively now," Amazon CEO Andy Jassy wrote.

Amazon chief executive Andy Jassy on Thursday justified the company's billions of dollars in outlays for artificial intelligence development, saying the investment was necessary to remain competitive.

Tesla could become the most valuable company in the world one day, according to Elon Musk, due to its upcoming Cybercab and ...