[Update 1: Provides more info on collateral.]

Freddie Mac confirms it will sell $1 billion in legacy, nonagency securitizations.

The assets were originated before conservatorship and Freddie Mac is mandated to reduce its portfolio size by the Federal Housing Finance Agency.

Freddie Mac reports the mortgages are investment grade, consisting of Alt-A and subprime paper.

The sale will come in June, with another billion being offered in July.

A Freddie Mac source said the sales may continue as long as it remains "economically sensible." However, the sales will not exceed $5 billion, the source said.

All of the collateral is currently in the performing bucket.