QuoteOriginally posted by: AminI asked the question in earnest. I remember when I did my thesis, I dealt with Bermudan constant tenor swaptions. They were different from regular bermudan swaptions in that they were far more sensitive to correlations between LIBOR rates when a model is properly calibrated to swaptions market. Though cms spreads were very popular before the crisis, I did not do any work on bermudan constant tenor swaptions so I really do not know about their liquidity etc. It just seemed natural to ask here.I guess that to price the CMS product you used Libor Market Model to account for the correlation, and then LS algorithm to account the callability feature. Only traders with high mathematical back round can trade these exotics products, thus they are illiquid. Also, keep in mind that trading with correlation sensitive derivatives can become very tricky as implied correlation is not in general being quote in BBG or RR (like implied vol). So, most of the times the prices in OTC market vary a lot.