• April 22, 2008

Silicon Valley startup Ning, whose software lets users create their own social networks, has raised $60 million in fourth-round funding led by Allen & Company. The funding gives the company a post-investment valuation of $560 million, according to a blog post by Ning co-founder Marc Andreessen.

He said the investment would help Ning continue its rapid expansion (over 230,000 networks on Ning now, growing at over 1,000 per day) and "make sure we have plenty of firepower to survive the oncoming nuclear winter."

Ning co-founder CEO Gina Bianchini is featured on the cover of the current issue of Fast Company, which contains a glowing profile of the startup. But skeptics have raised questions about whether the company's business model, which includes $20 monthly subscriptions, will match its hype.

--Mark Walsh