The bubble hasn't popped yet.
That's the easy conclusion of Forbes' latest Hottest Startups list, which ranks Silicon Valley's flashiest companies in 2015 by one simple metric: the fastest growing valuations over time between funding rounds. That means our list captures the most in-demand startups, the ones for which investors had the highest hopes--and wrote the biggest checks.
Combined, the top 50 hottest startups raised over $7 billion this year and have a total valuation close to $120 billion.
The list is headlined by a who's who of unicorns grabbing huge sums of cash. Ride-hailing juggernaut Uber (#16) is raising $2.1 billion to add to the $1 billion it raised in July. Workplace communication tool Slack (#2) raised $160 million, shared workplace landlord WeWork (#31) raised $433 million, and cybersecurity startup Tanium (#21) raised $120 million.
However, many startups at the top of the list are slightly off the beaten track. Secretive Uptake Technologies ranks first over all, coming out of nowhere to raise $45 million at a valuation of $1.1 billion. Uptake, run by former Groupon cofounder Brad Keywell, promises to provide the data analytics back end for the Internet of things revolution coming to major traditional industries like construction and aviation.
(Read more: How Uptake Beat Uber, Slack To Become 2015's Hottest Startup)
Home services network Porch, neighborhood marketplace OfferUp, and photo editing and sharing app PicsArt round out the top five along with higher profile Slack. Competitors DoorDash and Postmates both place in the top 10 this year, as investors sank lots of money into local delivery, despite the industry's huge cash burn and major past failures.
Some high performers on the list suffered setbacks even as they gathered large cash positions from venture capitalists. Zenefits followed up its number one overall rank in 2014 with a 10th place finish this year. After raising $500 million earlier this year, the cloud human resources startup admitted revenue was slower than expected in the third quarter. DraftKings (#15) used its funding to bombard televisions with daily fantasy sports advertisements, but recently hit a regulatory wall. And Theranos (#50) has endured skepticism surrounding its supposed breakthrough blood test technology.
(Read more: All 50 companies on this year's hottest startups list.)
The 2015 Forbes Hottest Startups list uses data from our partner, private company research firm Pitchbook. Only private companies that raised new funding rounds in 2015, analyzed via regulatory filings, were included.
