Lütkebohmert, Eva; Gordy, Michael B. - Deutsche Bundesbank - 2007
The credit value-at-risk model underpinning the Basel II Internal Ratings-Based approach assumes that idiosyncratic … risk has been diversified away fully in the portfolio, so that economic capital depends only on systematic risk … contributions. We develop a simple methodology for approximating the effect of undiversified idiosyncratic risk on VaR. The …