Indeed it sounds as impossible, but it is a reality. Even though it initially sounds as a very-very bad thing about the economy, it is the opposite. It means that investors believe that we will have inflation and they even accept a negative yield. So strong is their belief that prices will increase. This may prove right or wrong. This conviction is definitely due to the QE2. TIPS investors bet that the program will work and we will have inflation. Remember that for TIPS the face value is not fixed, like in Treasuries. The face value increases or decreases according to the inflation rate. Hence, negative yields can exist and it can be rationalized by a big probability of inflation, or higher values of inflation than previously thought, or both of the above.
Here I give some articles on this phenomenon. Article in Yahoo!Finance, in Bloomberg, in Reuters and in FT.
