The ad tech IPO market has dried up in the last 18 months.Public ad tech stocks have fallen 13% this year.
But the private ad tech market is still bustling. Plenty of ad tech companies are getting snapped up by larger firms, raising VC money (although, admittedly, some of the rounds aren't as big as they used to be), or simply steadily growing their businesses quarter-on-quarter.
Three of the companies on last year's ad tech startup ranking have since been acquired.
This ranking (and, yes, we were debating whether to lose the "pre-IPO" headline) looks at the hottest private ad tech companies right now.