THE $20 BILLION CLUB: Meet the 5 most valuable startups in the world

There used to be a time when a $1 billion valuation was considered a massive success for tech startups.

Then that threshold rose to $5 billion, and then $10 billion.

Looking at recent media reports and The Wall Street Journal's "The Billion-Dollar Startup Club" list, there are now over 100 "unicorn companies" - companies with $1 billion+ valuations. There's a growing number of "decacorn" companies, or startups with $10 billion valuations.

Now, there's a group of startups worth $20 billion or more. Here are the relatively new, private tech companies that are worth tens of billions of dollars - or that will be very soon.