The PetSmart retail chain has new owners and a new CEO. The equity firm BC Partners and a coalition of other financial backers today completed their $8.7 billion acquisition of Phoenix-based PetSmart. Stockholders received $83 a share, a 39 percent spike from July 2014, when investors began calling for a takeover because of what at least one critic called “years of underperformance.” PetSmart shareholders approved the deal Friday. Employing 53,000 people, PetSmart operates more than 1,400 stores in the United States, Canada and Puerto Rico. Many of the locations house a Banfield Pet Hospital veterinary clinic in an arrangement that is expected to remain in place. PetSmart’s new owners did not announce any changes other than the departure of President and CEO David K. Lenhardt. His replacement is Michael J. Massey, the former CEO of Collective Brands Inc., which owns the Payless ShoeSource chain. “My 15-year journey with PetSmart is filled with wonderful memories of our passionate associates who represent the best and brightest in retail,” Lenhardt said in a statement released by PetSmart. “I am confident that PetSmart will continue to lead the industry by creating more moments for people to be inspired by pets.” PetSmart in early March reported 2014 net sales of $7.1 billion, an increase of 2.8 percent compared with the previous year. Comparable-store sales rose by just 0.4 percent. Net income was $426.1 million, up 1.6 percent. Massey struck an optimistic tone. “I’m confident that PetSmart’s future will be one defined by growth, increased opportunities for our team and closer emotional connections with our customers,” he said. The sale to private investors brought to an end the trading of PetSmart stock on NASDAQ and the issuance of quarterly financial reports. PetSmart’s largest competitor, Petco, also is privately owned.