NEW YORK--(BUSINESS WIRE)--Fitch Ratings has updated its rating criteria for private student loan asset-backed securities (ABS). Primary changes include: --Seasoning credit for pools with less than two years of performance: Credit for seasoning will now be considered for pools with two years or less of repayment performance if the data provided is considered adequate. --Rating tolerance for surveillance: To avoid unnecessary rating volatility resulting from modest changes in credit performance