U.S. light-vehicle supply stood at near record levels on June 1 as General Motors stockpiled ahead of lower production planned for later this year.
GM's inventory jumped 43 percent from a year earlier to almost a million unsold cars and light trucks to start the month.
That was enough to push the overall industry's inventory to 4.18 million units, up 10 percent from June 1, 2016, and 19 percent higher than two years ago. May inventory was not quite as high as March's 4,191,700, which was the highest level since June 2004.
GM's stock growth accounted for 74 percent of the overall industry increase in June — up 291,400 units while all other automakers combined added 100,000 vehicles.
Measured by how long stocks would last at May's selling pace, the industry had a 69-day supply. That's 10 days higher than both May 2016 and the 25-year average for this time of year.
Typically, May is among the leanest of the year as manufacturers try to sell stocks for current model-year models ahead of midsummer production changeovers to the next model year.
GM stocks rose to a 101-day supply on June 1 from 99 days on May 1. Among the seven best-selling automakers, GM was the only one not to cut supplies during the month. Ford Motor, Fiat Chrysler US, Nissan North America and American Honda had double-digit declines, Toyota Motor Sales cut stocks eight days to 57 and Hyundai-Kia cut stocks two days to 54.
GM said it needs the extra inventory now because planned factory downtime for several upcoming redesigns will reduce second-half output by almost 100,000 units.