Mortgage-servicers are said to be the big sellers of treasuries this afternoon as rising US rates make mortgage holders less likely to refinance. This increases the duration of mortgage-bond portfolios which forces sales of Treasuries as a hedge. Marketwatch has a pretty good explanation. It is sort of like being short gamma in the options market. It forces you to buy strength and sell weakness, the opposite of what most would like to do.
US 10s have edged up to a 3.70% yield, the highest since last fall before quantitative ease was fully priced in.