10yr yields briefly hit their highest levels since May 23rd this morning after one large trade started a snowball sell-off in Treasuries.  Before that, modest weakness was already intact.

"A snowball sell-off to 4-month highs" sounds a bit more dramatic than the actual scope of weakness.  At the worst moments of the day, we were still looking at less than 3bps of losses in 10yr yields.  It didn't take long for buyers to take advantage of the yields, even though traders were contending with another big day of corporate bond issuance.  Making the rally slightly less impressive was the fact that stocks were selling at the same time, potentially adding a risk-off component to the move.

Ultimately, 10yr yields weren't willing to dip back below the 2.99% technical level and Fannie 4.0 MBS didn't manage to make it more than 1/32nd (0.03) back into positive territory.