Uber just reported its first-ever profitable quarter - but just how sustainable is it? GAAP net income was $394 million, but nearly all of that was due to a pre-tax benefit related to unrealized gains on Uber's equity investments. It holds stakes in self-driving tech companies Aurora, electric scooter startup Lime, ridesharing companies DiDi and Grab, and electric aircraft company Jovy. Its advertising business though is seeing new growth. It launched video ads on Uber, Uber Eats, Drizly and in-car tablets, reporting ad revenue run rate of over $650 million, and more than 400,000 active advertising merchants for the quarter.