GM's stock at last check dropped 8.1% to $19.09.
The numbers would likely be worse but for the timing of the coronavirus-driven economic shutdown. That began gaining momentum in March, the last month of the quarter, as federal and state governments escalated social-distancing restrictions.
GM in mid-March joined other major automakers in temporarily suspending vehicle production at its plants amid rising concern about the spread of the coronavirus on factory floors.
GM rolled out 618,335 vehicles during the first three months, down from 665,840 during the year-earlier quarter.
Buick models took the biggest hit, with deliveries dropping more than 34%, followed by Cadillac, which fell 15%, and GMC and Chevrolet, which eased 5.3% and 3.8%, respectively.
Some bright spots: GM reported a big jump in demand for two of its most popular light-duty pickup trucks. Silverado deliveries surged more than 33% to 112,925 and sales of the Sierra rose 27% to almost 40,000.
By contrast, deliveries of the midsized Chevy Colorado pickup truck hit the brakes, dropping 36% to 21,430.