Apparently, Groove was sold to Microsoft for $120 million in cash (via Dave) which falls short of $155 million invested into Groove. Since Microsoft was the largest investor, it's share out of the $120 million is about $80 million. That means Microsoft bought rest of Groove for just $40 million.
Groove investors got some of their money back for which founders gained some respect. Microsoft got a bargain (?!?) and a new CTO. And employees got nothing for their shares. Phew!