(AP)—Yelp's stock is passing one of its biggest stress tests since the online business review service went public nearly six months ago.
Shares are up nearly 18 percent to $21.46 during Wednesday afternoon's trading, signaling that the company's early backers have decided to hold on to their stock instead of selling at the first opportunity.
The first selling window for Yelp Inc.'s insiders opened with Wednesday's expiration of a ban requiring them to hold on to their stock for 180 days after the company completed its initial public offering in early March.
The end of other post-IPO "lock-up" agreements led stocks of Internet companies Facebook Inc. and Angie's List Inc. to plummet earlier this month as some insiders bailed out of the companies and flooded the market with more shares.
Explore further: Apple co-founder to mentor at Australian university