A herd of unicorns — startups valued at over $1 billion — are gathering in the Bay Area. Uber, Airbnb, Palantir... It's not often in human history that so much wealth has grown so quickly in one place.
There is a boom on. But economists say you can't call it a bubble till... well, until it goes POP. Today on the show: We visit three bubbly barometers that some say signal a coming bust.
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