These days, investors can’t help but write big checks to fund startups that have a shot at changing the world. To borrow some perspective from venture capitalist Marc Andreessen, “it can … be irresponsible to NOT invest to become #1 in a big new market.”

And so the tech press occasionally issues articles about startups with head-shakingly high valuations following extra-large funding rounds. The latest came yesterday, when a report suggested that a forthcoming funding round for Uber would value the startup at $35 billion to $40 billion.

If the report is true, Uber would be much closer to a recent $50 billion valuation for Chinese smartphone company Xiaomi and potentially even farther ahead of other hot companies that remain privately held, including Airbnb, Dropbox, and Snapchat. Square, Pinterest, Cloudera, Palantir, Spotify, and many others all lag behind the big five.

Companies rarely discuss valuations in public, so it’s difficult to provide definitive information. Still, the recent reports show which companies have some major potential.

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