Standard & Poor's released its residential mortgage-backed securities arrears data for the month of June yesterday, with a media statement saying prime RMBS arrears fell in June and sub-prime RMBS arrears rose. However, an analysis of the actual amount of arrears in terms of dollar value (rather than as a proportion of the face value of RMBS outstanding) tells a slightly different story. Looking at movements over the three months from the end of March is also insightful.A distinction also needs to be drawn between prime RMBS that includes internal securitisations for repurchase transactions with the Reserve Bank, and prime RMBS that does not.Looking at the change in sub-prime arrears since the end of March, arrears greater than 30 days have fallen as a percentage of the face value of subprime RMBS outstanding to 4.6 per cent from 5.4 per cent.However, this disguises an 8.6 per cent increase in the dollar value of arrears to A$140.4 million, as the face value of sub-prime RMBS has increased by more than $650 million to almost $3.1 billion.Of more concern is a 13.5 per cent increase in the dollar value of arrears greater than 60 days and a 12.7 increase in arrears greater than 90 days. These increases are hardcore and not just a temporary slip in making mortgage repayments.More sub-prime borrowers are getting into difficulty and are in danger of losing their homes. The same applies to some prime borrowers. In the case of prime RMBS, arrears since the end of March appear to have remained steady at 1.2 per cent of total RMBS, including internal securitisations. But analysis of the underlying numbers shows that arrears greater than 30 days have increased by four per cent to $1.4 billion. Again, it is the greater than 60 days and 90 days buckets that have increased the most, at 4.8 per cent and 8.2 per cent respectively.Curiously though, the growth in arrears appears to have occurred among the internal securitisation RMBS (the prime of the prime). The arrears data for prime RMBS excluding internal securitisations shows that the dollar value of arrears greater than 30 days was virtually flat, at $904 million. Moreover, arrears great than 60 days fell by 3.4 per cent, while arrears greater than 90 days rose by 2.5 per cent.