The Royal Bank of Scotland(RBS) is estimating how much the recent robo-signing allegations and knock-on effect will have on the operations of the big four banks: Bank of America (BAC), Citibank (C), JPMorgan Chase (JPM) and Wells Fargo (WFC). While several other sources put the estimations higher, RBS thinks these numbers are overestimated. Barclays(BCS) said earlier that the monetary damage due to reps and warranties alone could cost upward of $85 billion. RBS puts its total cost estimation at $42.3 billion. That includes up to $4.3 billion in settlement fees with the state attorneys general offices, repurchases of $25 billion and claims for reps and warranty breaches at $25 billion. "Outside of a discovery process, there is no systematic way of estimating how many loan file exceptions exist," states the securitized product strategy commentary released Tuesday. "However, based on our understanding of industry practices in 2005 - 2007, we would guess that perhaps 1% - 3% of loan files may be materially and adversely incomplete as a result of original documents that were never conveyed to the custodian." Write to Jacob Gaffney. The author holds no relevant investments.