STOCKHOLM—Ericsson’s top executive vowed to double down on efforts to regain market share lost in China after Sweden blocked Chinese suppliers from its 5G roll-out, a move that antagonized Beijing and has hit the equipment maker’s business. China accounted for about 10 percent of Ericsson’s revenue last year, but that fell sharply after the company’s home country of Sweden banned Huawei from its 5G networks, citing security risks—a charge that Huawei has strongly denied. Ericsson was awarded about 2 percent of China Mobile’s 5G contract, down from 11 percent last year, and got a 3 percent share in a joint 5G radio contract from China Telecom and China Unicom. “We have been in China for 120 years and I don’t intend to give up easily,” Chief Executive Borje Ekholm said in an interview with Reuters. “We are going to show that we can add value to China.” Ericsson had lobbied …