Standard&Poor's Ratings Services assigned its 'AA+/A-1+' rating to Iowa Finance Authority's (IFA's) series 2015B single-family mortgage revenue bonds. At the same time, Standard&Poor's affirmed its 'AA+' and 'AA+/A-1+' ratings on the authority's single-family mortgage revenue debt (mortgage-backed securities program). The outlook is stable. The 'AA+' long-term component of the rating on the 2015B bonds is based on the long-term rating on the bond indenture. The A-1+ short-term component of the rating on the 2015B bonds reflects an enhancement in the form of a standby-bond purchase agreement (SBPA) from Federal Home Loan Bank of Des Moines (A-1+) and our opinion of the likelihood that bondholders will receive interest and principal payments when due if they exercise their