FRANKFURT—Germany’s Commerzbank reported a $3.3 billion fourth-quarter loss on Thursday, sinking further into the red as it continued a major restructuring and dealt with the fallout of the COVID-19 pandemic. Its shares fell nearly 6 percent in mid-morning trade. Germany’s No. 2 bank also said it would swiftly implement plans to cut 10,000 jobs and close hundreds of branches, and would strive for an operating profit in 2021. Commerzbank hopes the revamp will revive its fortunes, as it struggles to boost profits amid management reshuffles and strategy flip-flops. It has never fully recovered after a state bailout during the last financial crisis more than a decade ago. The net loss of 2.70 billion euros ($3.27 billion) in the quarter compares with a loss of 97 million euros ($117 million) a year earlier. The bank had already disclosed that it lost nearly 2.9 billion euros ($3.5 billion) for the full year. …