It’s not just the supply boost that slowed wholesale vehicle values in May.  

Some of the decline, says ADESA chief economist Tom Kontos, was driven by flat used-car retail sales and a dip in certified pre-owned sales (albeit year-to-date CPO sales are still up and at a record pace).

“This limited the demand side support for wholesale values, which are already receiving downward pressure from supply growth,” Kontos said in his monthly video recap of the wholesale vehicle market (which can be seen in the window above).

Citing data from the National Automobile Dealers Association, franchised dealers saw their used retail sales fall 0.5 percent year-over-year in May, while independents were up 1.2 percent, he said in his May Kontos Kommentary report. Both showed significant month-over-month growth, however.

According to Autodata Corp., CPO sales in May dipped 4.6 percent year-over-year and 4.8 percent month-over-month, Kontos said. This was the second consecutive sequential decline.

“The bottom line is, we didn’t get the kind of demand side support we had been getting in previous months, this year and last year, to support wholesale used-car values,” he said.

Overall, wholesale values fell 1.4 percent month-over-month in May. Prices continued to beat year-over-year comparisons, with May prices up 2.4 from the same month of 2015.

“But even that is largely because of the price strength of trucks,” Kontos said.

Truck prices were down month-over-month in May (1.3 percent), but were up 5.8 percent year-over-year. Car prices softened 1 percent from April and 1.7 percent from May 2015.

Manufacturer consignment was fetching prices 2.5 percent higher on a month-over-month basis and 2.8 percent softer on a year-over-year basis, according to the ADESA report.

Fleet/lease consignment prices dipped 0.6 month-over-month and 0.8 percent year-over-year. Dealer consignment prices were down 1.9 percent from April and up 2.3 percent from May 2015.