General Motors Co. /zigman2/quotes/205226835/composite GM +2.79% said Wednesday that second-quarter deliveries fell 34.0% from a year ago to 492,489 vehicles, weighed down by the effects of the COVID-19 pandemic. Retail sales for the quarter fell 24%, as a 35% drop in April was followed by 20% declines in May and June. The auto maker said it will keep most of its U.S. plants operating, including all of its truck and sport-utility vehicle plants, during the traditional two-week summer shutdown period, as the company looks to restock inventory. GM said most of the increased output will be to restock retail channels, with capacity made available by lower rental volumes. Among deliveries for GM vehicle brands, total Chevrolet deliveries fell 33.6%, GMC declined 32.9%, Buick dropped 35.9% and Cadillac slid 41.4%. Within Chevrolet, the top models delivered were the Silverado LD, which fell 18.6% to 89,465 vehicles, while the top GMC model delivered was Sierra LD at 38,825 vehicles, down 9.5%. GM's stock slipped 0.4% in morning trading. It has gained 30.9% over the past three months, while the Dow Jones Industrial Average /zigman2/quotes/210598065/realtime DJIA +0.42% has rallied 23.3%.