Dorsey's Square jumps in market debut, offering hope to tech startups

Shares of Square Inc, the mobile payments company co-founded and still run by Twitter Inc Chief Executive Jack Dorsey, soared as much as 64 percent in their market debut, following a marked-down initial public offering, countering the negative sentiment that has nagged at Silicon Valley startups in recent weeks. The steeply discounted IPO price, at less than 60 percent of the company's last private valuation, had raised questions about the prospects of other so-called 'unicorns' - startups worth