State housing finance agencies are performing strong in both the single-family and multifamily bond-parity programs, according to Standard & Poor's. The credit rating agency hosted a teleconference Tuesday to outline the results from its most recent score cards. A bond-parity program is essentially an open bond program. As an HFA issues debt over time, the program builds equity and a larger financial cushion for lending. Over several years, the parity program can build multiple layers of equity, for example, 6% one year and an additional 4% the next year; however, bond parity programs are limited by the earned spreads. Analysts said, with regard to single family housing, three bonds have been rated positively and two have been rated negatively or downgraded over the past 16 months. Currently 40% of all HFA bond issuances are rated triple-A, and all but 6% are double-A minus or higher. Standard & Poor's said the biggest challenge facing the single-family bond market is a deteriorating credit quality, which is restricting credit opportunities for providers with lower ratings. Overall, analysts said that legislative change is having a positive effect on HFA single-family bond ratings. The multifamily HFA bond market is rebounding from a dissipating trend through 2008 and 2009, although the demand for low-income housing has decreased. Analysts said in some cases, the market for low-income housing bonds has completely disappeared. Standard & Poor's said the over-collateralization of multifamily bonds has increased to 48% from 39% one year ago. Bonds are also performing better because occupancy rates are high and loan-to-value rates are lower than previous months. Both over-collateralization and high occupancy rates build a parity's equity. There are a total of 15 HFA multifamily bonds issuances, all except for two of which have a double-A rating. In both sectors, increasing delinquency rates has not lead to a downgrade in ratings. Write to Christine Ricciardi.