In the wake of its failed $47.5 billion takeover bid for Yahoo, Microsoft apparently sent a calling card to Facebook, the social networking site, to see if it might be up for a deal.

In an attempt to to build on the software giant’s $240 million investment in the start-up last year, Microsoft’s bankers approached Facebook to see if it would be open to a full buyout, according to press reports.

In October, Microsoft took a $240 million stake in Facebook, which valued the start-up at $15 billion.

And while The Wall Street Journal said that there were no active talks between the two companies, Microsoft has reportedly approached Facebook several times since its investment to see if it was interested in doing a deal.

With its latest approach, Microsoft appears to have been re-testing the waters, rather than making concrete move.

“We just wanted to gauge their interest, more than any real effort,” a source told All things Digital, which first reported the talks.

The same unnamed source, however, told the publication that they expected Facebook to stick to plans for an eventual initial public offering.

Facebook, founded in 2004 by Harvard student Mark Zuckerberg, has become one of the hottest properties on the Internet because of its rapid growth and the loyalty of its users. Facebook has more than 70 million active users.

In the past, Mr. Zuckerberg has resisted selling the entire company, opting to work toward an I.P.O.