Bond markets began domestic hours only slightly weaker, but that didn't last.  Milliseconds into the 8am hour, we saw stronger inflation data in Europe and economically bullish comments in Yellen's prepared statement for today's congressional testimony.  Granted, Yellen is on the way out as Fed Chair, but her thoughts on the global economy are still quite relevant for several reasons (not the least of which being that she's a good indicator of the rest of the Fed's thinking).

Then at the 8:20am CME open (the first major window of liquidity and participation in bond markets) traders were lined up to sell.  This mini-snowball of tradeflows (traders cashing out their previous bets on a flattening yield curve) accounted for the remainder of the early morning market weakness.  The 8:30am GDP data had absolutely no effect (the move was over by 8:26am!).  

From there, bonds were largely flat for the rest of the day.  A late afternoon stock swoon in Europe translated to support for US bond markets, but definitely not enough to spark a rally.  It merely stopped the bleeding.  Corporate bond issuance and tax bill headlines kept the pressure on rates to remain elevated into the close.