Hi folks,I am working for the derivative valuations team of an investment firm, and need to value our CDX tranche positions (mainly iTaxx and DJCDX IG series) every month. We use the base correlation method proposed by JP Morgan, which implicitly requires input market data of the spreads and correlations from the Markit Partner. However, after the credit crunch, the Markit has stopped giving us anything for off-the-run tranches while our trades did not roll over. The Markit says that they could not get sufficient contributors for off-the-run tranches since they have not been actively traded, so they could not publish their spreads data. Is there anyone here familiar with this issue? Would anyone be able to give me some hints on where to get the data, or how to get around this problem? Your time is highly appreciated.We have been asking our trading counterparties' valuation team to give us broker marks of our trades. However, their quotes are hard to validate and can not really just be taken "as it is".. We have been thinking of exploring other data vendors e.g. creditflux or CMA, anyone here knows how good they are?We have also been thinking of building our in-house model system to either process the broker marks that we get from our counterparties, or interpolate the off-the-run tranche spread / base correlations using the on-the-run tranche data.. anyone knows how the Markit process data when they get quotes from the brokers? or any other firms' trick to get around with data insufficiencies?Thanks a lot,ah

off-the-run tranches = non-standard tranches?

No. Off-the-run tranches mean DJCDX IG4 to IG7, or HY4 to HY7, etc.. Anything that has not been rolled over as the index updates..