BDT & MSD Partners, an investment and advisory firm, is taking a majority stake in Sunrise Senior Living, the fifth largest senior housing operator in North America, while senior leadership at the privately held firm will own the rest. Sunrise operates more than 230 communities across the U.S. and Canada, serving more than 22,000 residents. The buyer values the deal at more than $1 billion, making it one of the largest senior housing deals since Covid disrupted the business in 2020.