The fourth wave of payments tied to the Independent Foreclosure Review settlement hit the mail Friday, bringing the total number of checks mailed to 3.9 million worth $3.4 billion.

Of those borrowers who received checks, more than 1.8 million have already been cashed or deposited for a total of $1.7 billion in completed payouts.

The fourth wave mailed Friday includes another 233,404 checks, totaling $224 million, the Office of the Comptroller of the Currency said.

The payouts are part of a deal federal regulators made with 13 servicers earlier this year.

In exchange for ending a national review of foreclosures, the regulators agreed to stop probing into older foreclosures and send a one-time payment to impacted borrowers instead.