DETROIT — General Motors’ U.S. light-vehicle sales fell 9.9 percent in the third quarter, as the automaker continues to face a shortage of high-demand pickups and SUVs. But GM’s crossovers posted significant gains, with sales of the Buick Envision, Chevrolet Blazer and Cadillac XT6 each climbing more than 40 percent from a year ago.

GM delivered 665,192 vehicles in the quarter, the automaker said Thursday.

“Inventory levels remain very tight, especially for pickup trucks. This is a function of the pandemic-related downtime, as well as strong demand for our products,” GM spokeswoman Lauren Langille told Automotive News. “We are currently running our full-size pickup truck and SUV plants at maximum capacity, and vehicles are being sold almost as soon as they arrive on dealer lots.”

Sales improved each month in the quarter, GM said, adding that sales rebounded significantly in September.

Of GM’s four U.S. brands, Buick fared best, down 2.9 percent from the third quarter of 2019. The new Encore GX subcompact crossover made up nearly a third of Buick’s sales, and volume of the Envision compact crossover rose 44 percent. Encore and Enclave sales declined.

GMC sales dropped 5.7 percent, including a 25 percent decline for the Yukon large SUV. Redesigned 2021 Yukons began reaching dealerships in June. Sierra pickup sales rose 2.4 percent, driven by a gain for heavy-duty models, to the nameplate’s highest third-quarter volume ever, GM said.

Chevy sales fell 11 percent, but sales of the Blazer midsize crossover jumped 45 percent. Chevy sold 10,322 of the new Trailblazer in the quarter.

Cadillac sales fell 18 percent as the brand phases out the CT6, CTS, XTS and ATS. Sales of the XT6 large crossover climbed 45 percent, while Escalade sales sank 56 percent amid a changeover to the redesigned model.

Low inventory levels have concerned many GM dealers since plants shut down in the spring in response to the coronavirus pandemic. GM said it remains focused on building the right mix of vehicles to meet demand. Large pickup and full-size SUV plants are running on three shifts with maximum overtime.

Brands: Cadillac down 18%; Chevrolet down 11%; Buick down 2.9%; GMC down 5.7%.

Notable nameplates: Cadillac Escalade down 56%; XT4 down 29%; XT5 down 23%; XT6 up 45%; Chevrolet Blazer up 45%; Bolt EV up 18% ; Camaro down 32%; Colorado down 14%; Corvette up 33% ; Equinox down 15%; Malibu down 22%; Silverado down 5.3%; Suburban down 39%; Tahoe down 12%; Trax down 21%; Traverse down 23%; Buick Enclave down 25%; Encore down 55%; Envision up 44% ; GMC Sierra up 2.4%; Acadia down 10%; Canyon down 13%; Terrain down 7.6%; Yukon down 25%.

Incentives: $5,698 per vehicle, up 9.8% from a year earlier, ALG says.

Average transaction price: $41,515, up 3.4% from a year earlier, according to ALG.

Fleet mix: GM expects its low fleet sales to recover but not as quickly as retail sales have, Langille said. Although volume has declined, GM’s fleet market share is up about 2 percentage points year-to-date, and commercial and government sales have remained relatively consistent during the pandemic, she said. Rental car volume has been hit the hardest industrywide, but Langille said the rental industry is looking for volume to prepare for early next year.

“At the end of the quarter, we started to see some rental demand, which is an encouraging sign,” she said.

Quote: “Our dealers are doing exceptionally well utilizing a combination of customer-facing online technologies — such as Shop. Click. Drive. — and showroom sales to deliver vehicles safely to our customers. This is contributing to retail share gains while we continue to refill the pipeline,” Kurt McNeil, vice president of U.S. sales operations, said in GM’s statement. “Industrywide, dealers are selling a high mix of large pickups as the summer comes to an end. Our strong large pickup and all-new full-size SUV lineups from Chevrolet and GMC are selling extremely fast.”

Did you know? Nearly 40 percent of Trailblazer buyers are new to Chevy. Chevy says the Trailblazer is the industry’s fastest-turning new vehicle.