PSA spread

Hey everyone! Sorry to bother again but I’m having trouble with this problem from my text book and I was wondering if anyone could help me out!: PSA spread of 352, with 50 months left and I need the SSM= ________ and the CPR=________ Thanks for the help ahead of time :slight_smile:

I don’t know what PSA spread 352 means (possibly the speed or months). Anything after 30 months has a CPR of 6%. SMM = 1 - (1-.06)^(1/12) = .00514 = .514% Is this right?

the PSA will speed up prepayment, as the solution provided by niblita assumed PSA of 100. thus SMM and CPR will be a multiple of 3.52

Ah, I just have never seen it written that way. I usually just read it as PSA 352. My bad. CPR = .06 * 3.52 = .2112 = 21.12% SMM = 1 - (1- .2112)^(1/12) = .019576057 = 1.9576057% Edit: Good call got lazy.

I don’t think it will be a straight multiple of 3.52, the equation is non-linear


yep, your right cardshark, my fault there…got a bit silly there in my explanation.