NEW YORK--(BUSINESS WIRE)--Fitch Ratings has upgraded WM Covered Bond Program's (WMCBP) mortgage covered bonds to 'AA+' from 'AA-' with a Stable Outlook. The Stable Outlook for the covered bonds rating is primarily driven by the Stable Outlook on the U.S. sovereign and on JP Morgan Chase N.A.'s (JPM) Issuer Default Rating (IDR). The upgrade to 'AA+ ' is driven by lower credit losses on the cover pool and program sponsor JPM's Fitch's IDR of 'AA-', which means that interest rate stresses at this