Mortgage investor research firm, Amherst Securities, released its monthly monitor report on the secondary market noting a huge jump in prepayment risk in the nonagency space.

Voluntary refinances, not linked to Fannie Mae and Freddie Mac are up from 11.6% yearly last month. They were up from 10.4% in April 2012.

Amherst originally expect this number to remain flat, as with government-sponsored enterprise data.

"The fact that prepayments were up substantially was due in part to clean‐up calls, but this alone is insufficient to explain the magnitude," the report states.

"This trend appears to be broad‐based across the major bank servicers, introducing the possibility that borrowers may be relying on home price appreciation headlines to re‐examine their refinancing opportunities," the text continues. "If this is the case, we should see a base upward trend in prepayments over the next few months, despite slightly higher driving rates."