Microsoft Is Said to Agree to Purchase Yammer for $1.2 Billion

Microsoft Corp., the world’s largest software maker, has agreed to purchase Yammer Inc., operator of a social network for businesses, for $1.2 billion, said a person familiar with the matter.

The deal is expected to be announced by the end of June, said the person, who asked not to be identified because the negotiations are private. Dee Anna McPherson, a spokeswoman for Yammer, declined to comment on a potential acquisition, as did Frank Shaw, a spokesman for Microsoft.