Quote from mcurto:
Newbunch,
All of the bond mutual funds such as PIMCO, WAMCO, Vanguard, etc., etc., benchmark their returns to the Lehman bond indices. Therefore as the Lehman bond indices add the new 10s and 30s that were auctioned this month they will cause duration in the index to increase more than a normal month (around .08 or so usually). Since the aforementioned funds performances are based off the Lehman bond indices they need to match that performance. Thus they buy the same bonds or their futures equivalents that were added to the Lehman indices. Don't worry about the .21 number other than that it is much more than normal. Be careful getting super long into the close tomorrow, sometimes dealers will fade this end-of-month move and other times will just continue to bid it into and after the close. There will definitely be huge size on the last minute bell both in the pit and on the screen, so could be pretty fun if you are on the right side.