– UnitedHealth Group Inc. took center stage in the bond markets Monday by selling $10.5 billion in bonds that attracted more than $40 billion in orders.

Minnetonka-based UnitedHealth plans to use the proceeds to help pay for its $12.8 billion purchase of pharmacy benefit manager Catamaran Corp., which was announced in March.

There has been plenty of appetite among bond buyers for debt issued by health insurance companies, a sector that's in the midst of a spree of deals.

"Of all the consolidation going on in the sector, it is in our view one of the best in-class names," said Shubhomoy Mukherjee, a health care strategist at Barclays. "They don't need to do large M&A transactions to maintain their growth momentum."

While UnitedHealth's leverage will go up meaningfully, Mukherjee said the company plans to reverse some of that by suspending its share buyback program and paying down debt with free cash flow.

Other health insurance entities have been on an M&A spree of late, with Aetna making a $33 billion bid for rival Humana and drawing the interest of antitrust regulators.

Earlier this year, UnitedHealth also sought to make a bid for Cigna.

The company raised the $10.5 billion in eight issues: a $750 million, 18-month floating-rate bond at LIBOR plus 45 basis points, a $750 million two-year at Treasuries plus 75 basis points, a $1.5 billion three-year at plus 85 basis points, a $1.5 billion five-year at 100 basis points over, a $1 billion seven-year at 125 basis points, a $2 billion 10-year at plus 140 basis points, a $1 billion 20-year at 150 basis points over and a $2 billion 30-year at 165 basis points.