While MBS managed to remain 1 tick in positive territory today, Treasury yields were higher on the day and the overall mood in bond markets managed to remain downbeat for yet another day.  For all intents and purposes, the driving force was simply ongoing "corrective" momentum from the same old correction that's been underway for a week and a half.

There were a few economic reports this morning (Housing Starts and Building Permits--stronger than expected and Import/Export prices--higher than expected), but neither had a noticeable impact on bond trading.

The 9:30am NYSE open was visually the starting point for today's selling pressure.  This reiterates the points above about "corrective momentum" and the unimportance of the econ data.  Simply put, traders wore their selling hats to the office today.  The weakness was the default game-plan, notwithstanding a surprise market mover to help bonds find their footing.  

Whether slightly weaker or stronger, the next big move continues to depend on tomorrow's Fed events.  These include the announcement itself, as well as updated Fed forecasts and a Yellen press conference.