Microsoft got LinkedIn's users at a discount

Microsoft's $26.2 billion deal to acquire LinkedIn came at a time when the professional social network's users were valued at less than ever before.

Before the deal's announcement Monday, the market's valuation of a unique visitor on LinkedIn was languishing around $165. That's the lowest price in the company's history for each unique visiting member — a metric comparable to the monthly active users reported by companies like Twitter and Facebook.

The same is true for total registered members, another metric that records anyone who has ever made a LinkedIn profile. (CNBC calculated per user value by dividing the company's market value by the unique visiting members reported for each quarter.)

LinkedIn suffered a vicious stock market rout of more than 40 percent in February after issuing weak guidance for the next year. Microsoft's offer propped up the stock with a 50 percent premium, placing the value of each of the company's 106 million visiting members at $247 each. That's a big boost, but still 10 percent lower than the company's average over its lifetime.

That premium places the network's users slightly above the per unique user valuation for Facebook, which had pulled ahead during the company's weak performance so far in 2016. Twitter's per user valuation has been dropping since its initial public offering at the end of 2013.

All three social networks have seen their user bases grow substantially over the last three years. Twitter's monthly counts are up 52 percent, Facebook is up 49 percent and LinkedIn has gained 63 percent in monthly users and nearly doubled in users overall.

The challenge facing all three companies is convincing investors that they'll be able to effectively monetize those massive groups of users. Facebook has soared to new highs this year by demonstrating that its ad network can wring real earnings out of its 1.7 billion monthly users.

In response to questions about whether the company was getting LinkedIn members at a bargain rate, a Microsoft spokesperson noted that the premium and revenue multiples the company is paying in the deal are well within the range of recent cloud software transactions. A LinkedIn representative declined to comment.

LinkedIn's business model differs significantly from the other two social network companies in that it not only makes money from ads but also charges membership fees for its premium product. Its biggest segment is talent solutions, which includes professional recruiting and job posting services.

Those additional revenue streams mean that each person added to the network is worth more than a user who provides revenue through advertising alone. It also means that for some users, simply signing up and filling out a profile has value even if that user doesn't sign in every month.

CNBC calculated the per user revenue rate by dividing the quarterly revenue for each company by the quarterly unique visiting members (for LinkedIn) or monthly active users (for Facebook and Twitter). While LinkedIn has always had the highest per user revenue rate, the company hasn't seen the sort of per user revenue growth that the other two networks have seen over the last three years.

Working with Microsoft could help LinkedIn find more uses for its unique user data and give it a chance to expand its user base at a more accelerated pace.

"Mostly, the Street had lost confidence that LinkedIn would be able to significantly diversify its business," wrote Evan Wilson and Tyler Parker in a note for Pacific Crest Securities on Monday. "A partnership with Microsoft gives us new hope."