The decrease brought the index to 194.5, a 19% increase from a year ago. The seasonal adjustment caused the monthly decline as the non-seasonally adjusted average price increased 1.4% in August, which left unadjusted prices up 20% year over year.

In recent years, August has seen large vehicle value increases, which is why the seasonal adjustment is producing the lower value when the market is seeing real prices rise.

Manheim Market Report (MMR) values saw changing trends in August that resulted in stable prices and then accelerating weekly increases. Over the last four weeks, the Three-Year-Old Index increased a net 2.1%.

During August, MMR Retention, which is the average difference in price relative to current MMR, averaged 100%; but the first weekday of the month saw 98.8% retention, while the final weekday saw 100.9% retention, which means market prices are now ahead of MMR values when they started the month below.

The sales conversion rate also increased in August and ended at a level higher than typical for that month, indicating buyers have become more aggressive than they were in June and July.

On a year-over-year basis, all major market segments saw seasonally adjusted price increases in August. Vans and sport utility vehicles had the largest year-over-year performance, while the remaining car and pickup segments lagged the overall market. On a month-over-month basis, the compact car and pickup segments saw declines, while the remaining segments saw modest growth.

Vehicle sales fall: According to Cox Automotive estimates, total used vehicle sales were down…