5. Securitization of Receivables

The following summarizes certain transactions with our securitization trusts:

In connection with securitization transactions, we typically retain servicing responsibilities and residual assets. In certain instances, we receive annual servicing fees of up to 0.20% of the outstanding balance. We may periodically make servicer advances, which are subject to credit risk. Included in other assets in our consolidated balance sheets are our servicing assets at amortized cost, our residual assets at fair value, and our servicing advances at cost, if any. Our residual assets are subordinate to investors’ interests, and their values are subject to credit, prepayment and interest rate risks on the transferred financial assets. The investors and the securitization trusts have no recourse to our other assets for failure of debtors to pay when due. In computing gains and losses on securitizations, we use the same discount rates we use for the fair value calculation of residual assets, which are determined based on a review of comparable market transactions including Level 3 unobservable inputs which consist of base interest rates and spreads over base rates. Depending on the nature of the transaction risks, the discount rate ranged from 4% to 7%.

As of December 31, 2017 and December 31, 2016, our managed assets totaled $4.7 billion and $3.9 billion, respectively, of which $2.7 billion and $2.3 billion, respectively, were securitized assets held in unconsolidated securitization trusts. There were no securitization credit losses in the years ended December 31, 2017, 2016, or 2015. As of December 31, 2017, there was approximately $1.1 million in payments from certain debtors to the securitization trusts that was greater than 90 days past due. The securitized assets consist of receivables from contracts for the installation of energy efficiency and other technologies in facilities owned by, or operated for or by, federal, state or local government entities where the ultimate obligor is the government. The contracts may have guarantees of energy savings from third party service providers, which typically are entities rated investment grade by an independent rating agency. Based on the nature of the receivables and experience-to-date, we do not currently expect to incur any credit losses of our residual interests related to the receivables sold.