Microsoft CEO Steve Ballmer reportedly is buying San Francisco-based Yammer.
While Yammer CEO David Sacks is reportedly preparing to celebrate his 40th birthday in style, his professional social network has agreed to be acquired by Microsoft.
Microsoft will reportedly purchase the San Francisco-based social network for business for $1.2 billion, according to The Wall Street Journal.
It is unclear when the deal would close, according to the paper.
Yammer was launched in 2008 and it has been used by companies to create an internal social network.
It has been called the Facebook for companies because they can control who signs up for the service by using corporate email domains as a form of identity.
Yammer has about 400 employees.