...OVERVIEW + We raised our ratings on four classes to '### (sf)' and affirmed our '### (sf)' and '##+ (sf)' ratings on six classes from eight ABS transactions backed by FFELP student loans. + The upgrades to '### (sf)' reflect our view of the increased credit enhancement levels (all with parity above 115%), positive collateral performances, and structures that generally do not allow releases until the notes have been repaid. + The affirmations reflect our view that the transactions' current credit enhancement levels, which are increasing, are sufficient to support the ratings. NEW YORK (S&P Global Ratings) Jan. 18, 2018--S&P Global Ratings today raised its ratings on four classes issued from four student loan asset-backed securities (ABS) transactions. At the same time, we affirmed our ratings on six classes from four other student loan ABS transactions (see list). Our review considered the transactions' collateral performance, changes in credit enhancement, and capital and payment structures....