Shares in Fortescue Metals lost more than 6 per cent on Thursday after it downgraded its iron ore production target and pushed back the timing of an asset sale.
On the day new manufacturing data suggested the economy of the world's biggest consumer of iron ore, China, was slowing, Fortescue revealed this year's export volumes would be as much as 4.75 per cent below previous estimates.
Rather than producing between 82 million and 84 million tonnes, it now expects to produce between 80 million and 82 million tonnes in the year to June 30.
The sale of a stake in Fortescue's rail and port assets has been keenly anticipated by investors who want the miner to reduce its $US10 billion ($10.8 billion) debt pile. The sale was expected to be finalised before June 30, but Fortescue said the process would be pushed into the September quarter.
That sale is hoped to deliver close to $US3 billion to the company. Its organisation so far has taken nine months.
With iron ore prices tipped to fall, many analysts believe Fortescue needs to sell that stake if it is to meet debt obligations between 2015 and 2020.
Fortescue chief executive Nev Power said the company would consider "further third-party investment in assets outside our core mining operations".
Fortescue produces iron ore at a higher price than Pilbara neighbours such as BHP Billiton and Rio Tinto, and the company has recently been borrowing billions of dollars to fund expansions designed to bring down the company's overall production costs.
Spending on expansions is almost complete and the company said free cash flow would soon improve dramatically, and help pay down the debt pile.
"Fortescue is now in a phase of significant cost reduction and continues to focus on operational efficiencies which will see it moving down the global cost curve," it said.
The comments about cost reduction come in the same week Rio Tinto made nearly 50 senior staff at its West Australian iron ore business redundant.
That business is considered best in class and made $US9.2 billion in profits last year, demonstrating no business in Australia is now immune from redundancies.
Sources close to Fortescue believe redundancies are unlikely in the near term, despite the changes to be made in the next year as the company moves from expansion mode to steady-state operations.
Aside from revealing lower iron ore production for the 2013 financial year, Fortescue also provided guidance on iron ore production for the year to June 30, 2014.
It expects to export between 127 million and 133 million tonnes of high-moisture iron ore in 2014, a figure in line with estimates published by RBC Capital Markets.
The price of Fortescue shares closed 22¢ down at $3.14.