The 90-day delinquent inventory of Bank of America (BAC) subprime mortgages have spent an average 552 days without some sort of resolution, according to a study released Friday by Moody's Investors Service. The credit ratings agency studied the six largest prime and subprime servicers, based on data reported by residential mortgage-backed securities trustees from June 2010 to June 2011. Combined, these firms service 75% of the market. Moody's findings mirror the early Fannie Mae mid-year report card. Both highlighted the poor performance of BofA and JPMorgan Chase (JPM) along nearly every metric. Analysts measured the banking giants' ability to keep loans current, and how long these loans have gone without a modification, short sale, deed-in-lieu or foreclosure once the loan turned delinquent. The servicers were also measured on their speed of liquidation once the property was repossessed.