Freddie Mac will begin creating new “mirror” securities that will play a key role in how the government-sponsored enterprise will allow investors to exchange existing Freddie participation certificates for new single securities. The mirror securities will be held in a Federal Reserve account and will not increase the outstanding principal balance of Freddie MBS, the GSE explained in an update on the exchange program. The mirror securities will track existing Freddie MBS but substitute a 55-day payment cycle for Freddie’s current 45-day cycle. When an investor exchanges part or all of an existing 45-day security for a new 55-day single security that’s interchangeable with Fannie Mae single securities, Freddie will pay...