Blackstone Group LP’s Invitation Homes, after spending more than $9 billion in a U.S. property-buying spree, is starting to sell some houses as it shifts focus from rapid expansion to fine-tuning its holdings. The housing landlord has agreed to sell about 1,300 Atlanta-area residences that don’t fit its strategy, which targets communities with higher rents and quality schools, according to Chief Executive Officer John Bartling. “It’s that stage in our lives where we’re now in a position of looking at dispositions as an active part of portfolio balance,” Bartling said in an interview.