Tech companies are continuing to garner major investments from venture capitalists. Major tech startups like Uber, Airbnb, and SpaceX are among the most highly valued private companies, PitchBook reports. But recent major investments into burgeoning tech startups — including Slack, Instacart, and Stripe — have brought new players into the spotlight. At this point, there are almost too many billion-dollar startups to count. Uber's $72 billion valuation solidifies the company's spot at the top. However, the rideshare platform plans to go public next year, so the No. 1 spot will soon be up for grabs.