Rates were little changed Monday as investors showed little reaction to a better-than-expected Chicago Purchasing Managers Index. The Chicago PMI national manufacturing index came in at 50.0, the dividing line between contraction and expansion. This may be a volatile week for mortgage-backed securities (MBS), with tomorrow’s release of the Institute for Supply Management manufacturing index, Wednesday’s release of the minutes from last month’s Federal Open Market Committee meeting, and Friday’s Non-farm Payrolls report for August. Any reaction to Friday’s employment data will be exaggerated due to an early market closing and light trading ahead of the Labor Day weekend. No other data will be released today.