Part online business directory, part customer reviews hub, Yelp has become indispensable for 108 million active monthly users since ex-PayPalers Stoppelman and Russel Simmons started it in 2004.

Jeremy Stoppelman is the CEO of Yelp and in March 2012 he took his company public. After a successful first day on the stock market, the stock bounced up and down for months, particularly around ...