... as a result of yesterday's FOMC policy announcement? This, from today's Wall Street Journal "Credit Markets" column (page C6), seems like a pretty reasonable explanation:
"The [Fed's] downgrading of inflation risk was bullish for longer-dated Treasurys," which are highly sensitive to the risk posed by inflation, said Richard Gilhooley, senior bond-market strategist at BNP Paribus.
At least I can't think of a better explanation. Let's see if it holds.