Blackstone Group LP, stepping up bets on Spain’s economic recovery, is buying about $8.7 billion of mortgages from CatalunyaCaixa SA for $4.87 billion.

Blackstone was the winner in the process known as “Hercules” that began in April, Barcelona-based CatalunyaCaixa said Thursday in an emailed statement. As many as 12 funds participated in the initial round and four groups presented binding offers, the lender said.