LinkedIn shares are up more than 20 percent today, to their highest levels since the professional social network went public, thanks to quarterly results that showed strong growth throughout the business and that blew past Wall Street expectations.

LinkedIn shares jumped 22 percent Friday. Image: Yahoo Finance

LinkedIn reported adjusted earnings of $40 million, more than tripling its performance last year, and revenue of $304 million, up 81 percent. Wall Street analysts had expected roughly half as much profit on revenue of $280 million. In mid-day trading the stock was near $151, versus its prior high of $127 last week and versus its IPO price of $45.

Also pleasing investors was how LinkedIn seems to be growing new businesslines successfully. Its core, longstanding recruiting business, in which LinkedIn provides special data to corporate headhunters, grew 90 percent. But LinkedIn’s newer advertising business also saw sales jump, by 68 percent, as pageviews grew almost the same amount. Those clicks came thanks to career advice and other professional content LinkedIn has been developing.

One area of possible concern: Mobile growth was quite modest, with some 27 percent of users on mobile devices in the fourth quarter, up from 25 percent from the prior quarter and 15 percent last year. And membership growth has been a modest 8 percent a quarter over the past three years, meaning it could be some time before LinkedIn is firmly entrenched as a solid "second social network" used in parallel with Facebook. Investors, for the moment, don’t seem at all worried.