Last week, the professional social network service LinkedIn filed for its IPO, expecting to raise $175 million from the capital market. The company's stock could be traded publicly any time soon as we speak. LinkedIn's IPO, alongside with Facebook's shares being actively traded in the private market and other social media firms' soon to be expected IPOs, indicates the long-time nascent social media market is approaching a watershed moment that social media business finally becomes finacially viable and profitable. 

The Internet world has marched through 3 phases so far, from the era of web portals, where AOL and Yahoo-like websites served as the main gate of Internet, to the emergence of search engines and now to the age of social media. The IPO of Google in 2004 carved a sign of maturity on the search business in a sense that search could be an independent and financially viable business. The same doubt was placed on social media companies as well in the early stage of the business when sites like Facebook and Twitter generate a tremendous number of pageviews and gain millions of users with incommensurate level of revenues. Advertising is always a key revenue stream for Internet business, but the small amount of ad revenue on social networking sites compared with their large user bases forces these companies to look for other income streams. 

LinkedIn has figured it out. The professional network has seen almost 100% revenue growth in 2010, providing a strong evidence to our social networking market growth forecast published last year. Among the three major revenue streams LinkedIn has, advertising or marketing solutions by their terms accounts for 32% of total revenues in 2010. They generated 27% of their sales from subscription service, and the biggest portion 41% came from hiring solutions, which is primarily derived from the sale of corporate solutions and job products. It is also expected that LinkedIn's future growth heavily relies on the hiring solution segment. If we project a 20% annual growth for the company, we would see it become a $500 million company in 2015. The kid of social media finally matures. 

I'd also like to share some stats on US social media users.

Client Reading: Social Network Market Forecast, Profiling the US Social Network Users