BUMA has paid Downer a deposit of $16 million with the remainder of the purchase price payable at completion, which is expected by the end of the year.

The transaction includes the transfer of the assets, liabilities (including employee entitlements), employees and contracts comprising the Open Cut Mining East business to BUMA.

It comes after Downer sold its Open Cut Mining West business to MACA late last year for $175 million.

The BUMA deal takes the total proceeds of Downer's divestment program to $778 million.

"An important part of our Urban Services strategy was the exit from our capital-intensive mining businesses," Downer CEO Grant Fenn said.

"The sale of Open Cut Mining East is the last step of this process and follows the divestments of Open Cut Mining West, Downer Blasting Services, Underground mining, Otraco, the Snowden consulting business and our share in the RTL Mining and Earthworks joint venture."

Downer shares closed at an 18-month high of $6.76 on Friday, valuing the company at $4.7 billion.