Market risk capital (MRC) is derived from value-at-risk (VaR) and a tail-loss penalty based on backtesting results. The Basel II approach to calculating the tail-loss penalty (K-factor) does not adequately account for the magnitude of losses beyond VaR. An alternative approach by Blanco-Ihle defines tail losses as a percentage breach from VaR conditional on a breach. This allows calculating the K-factor based on either the maximum tail loss (KBI.max) or the average tail losses (KBI.mean). Backtesting results for RAS portfolios in early 2012 show the KBI.mean approach provides a more realistic assessment of tail risk compared to the Basel