While pinpointing a trio of subprime securitizations demonstrating some higher loss trends, S&P Global Ratings determined collateral performance in the U.S. auto loan asset-backed securities sector improved month over month in April for the subprime sector, but continued to remain weak on a year-over-year basis for both the prime and subprime sectors.

Analysts recently explained the overall trends continue to reflect seasonality and a change in portfolio composition.

In the subprime sector, S&P Global Ratings determined net losses, 60-plus-day delinquencies and the recovery rate improved month over month. However, the firm noticed both the prime and subprime sectors experienced higher losses and delinquencies, and lower recoveries year over year.

S&P Global Ratings credit analyst Amy Martin mentioned the subprime static pool index is showing weaker cumulative net loss performance, particularly for the 2014, first-quarter 2015, second-quarter 2015, and third-quarter 2015 vintages.

“We attribute these higher losses primarily to changes in the composition of the subprime index in the past year,” Martin said. “We believe that these higher net loss trends can be largely attributed to Drive Auto Receivables Trust (DART), ACA and Exeter.”

In the prime sector, S&P Global Ratings said this segment showed stable month-over-month performance, with net losses and 60-plus-day delinquencies remaining flat and recovery rates increasing slightly.

Analysts added the prime static pool index had been showing stable performance, with 2014 cumulative losses in line with 2013. However, S&P Global Ratings acknowledged cumulative net losses for the first-quarter and second-quarter 2015 vintages are showing greater losses compared with previous years.