LinkedIn last night said it expected its revenues for this year to below Wall Street's expectations, underscoring concerns about its ability to sustain its rapid growth and helping to drag its shares more than 3% lower. 

The social networking company, which is geared toward connecting professionals with prospective employers, predicts revenue of $500-$505m this quarter, compared with an average Wall Street forecast of $505.1m.

For all of 2014, it expects sales of $2.06 billion to $2.08 billion - up from a previous forecast, but still lagging analysts' $2.11 billion target.

LinkedIn's tepid outlook overshadowed a higher than expected 46% increase in first-quarter revenue to $473.2m, comapred to the $466.6m expected by analysts on average, according to Thomson Reuters.

LinkedIn has rapidly expanded from an online gathering place for professionals to a provider of a plethora of employment services, and it is now mining mobile advertising, marketing solutions and original content for new revenue.

It is also trying to replicate its US success internationally. 

In February, it launched a Chinese language "beta" version of its main website, in the hope of jump starting an expansion into the world's largest Internet market by users. However, the company acknowledged it will have to police what some of its members say on the website. 

Wall Street has high expectations for a company still growing its top line at strong double-digit-percentages, while attracting new members to its expanding network. 

LinkedIn's membership rose 8.3% to 300 million worldwide from 277 million at the end of the fourth quarter. That pace accelerated slightly from 7% in the fourth quarter a year ago.

LinkedIn's fourth-quarter revenue missed Wall Street's target, the first time it has fallen short on a quarterly basis since it went public in 2011.