some startups become big and they become unicorns, i.e. privately held startup companies valued at over us$1 billion. the term was coined in 2013 by venture capitalist aileen lee, choosing the mythical animal to represent the statistical rarity of such successful ventures. according to "techcrunch", there were 452 unicorns as of may 2019, and most of the unicorns are in the usa, followed by china. the unicorns are concentrated in a few countries. the unicorn leaders are the u.s. with 196 companies, china with 165, india with 65 and the u.k. with 16.