The move will help the cash-strapped coal and iron ore miner to continue operating for the short term.
Casablanca Capital Mining News
But the miner revised down its 2015 U.S. iron ore sales and production volume estimate to 20.5 million tons, from its previous guidance for 22 million tons
Chief Executive Lourenco Goncalves said restructuring proceedings have begun in Montreal and sale options will be explored.
It also said it has reduced its net debt balance by more than $400 million.
Active production at the Canadian Bloom Lake iron ore mine has completely ceased, and the sale of the firm's its struggling coal division has been completed.
Miner is dropping coal operations to focus on iron ore.
About 500 workers will lose their job.
The miner said the move was driven by its revised pricing outlook and adverse market conditions.
The new repurchase program will remain active until Dec. 31, 2015.
Casablanca Capital-backed Lourenco Goncalves (55) is also the new chairman of the board.
The fund, with just a 5.2% stake in Cliffs, has vowed to sell or spin the miner's international operations.
The firm is halting its Pinnacle metallurgical coal mine in West Virginia for at least six months, unless market conditions improve.
The miner's negotiations with one of its major shareholders has turned ugly.
Activist hedge fund takes 5.2% of Cliffs Natural Resources, tells miner to spin off international assets
The company is using its position as one of the biggest share holders to push for some major changes.