BEST DAY EVER

Facebook Stock Surges

Climb 21 percent in biggest gain since IPO.

Mark Zuckerberg made some friends. Facebook shares are on track to have their biggest daily gain since the initial public offering in May. The stock rose 21 percent to $23.57 in midday trading on Wednesday. The surge comes a day after the company announced a surprising increase in third-quarter revenue from sales of mobile ads. The mobile ads accounted for 14 percent of total revenue, an increase from none a year earlier. Through Tuesday the stocks had fallen 47 percent from the IPO price of $38. Bank of America analysts wrote that Facebook “can effectively grow revenues while usage transitions to mobile platforms from [personal computers].”