Sirius' shares fell to 4.4p by midday Tuesday, down from 10p on Monday.
Sirius needed to raise US$500 million via a bond sale to secure a $2.5 billion loan facility from JP Morgan, which would have funded development of the project.
The company said on August 6 it had postponed the proposed note issuance due to market conditions. Today's announcement shows appetite for the bonds has not improved.
"There has been no material change for an issuer like Sirius and the company is not aware that any significant new issuer in the same B/B- credit range that has come to market," the company said in a statement on Tuesday.
"Due to the ongoing poor bond market conditions for an issuer like Sirius we have not been able to deliver our stage 2 financing plan. As a result, we have taken the decision to reduce the rate of development across the project in order to preserve funding to allow more time to develop alternatives and preserve the significant amount of inherent value in this world-class project," Chris Fraser, CEO of Sirius, said in a statement.
Mining Journal reported earlier this month that Sirius would face administration should it fail to raise the necessary funds.
Fraser said the company would now conduct a six-month strategic review "to assess and incorporate optimisations to the project development plan and to develop a different financing structure for the funds required".
"This is the most prudent decision to give the company the time necessary to restructure its plans to move the project forward. The process will incorporate feedback from prospective credit providers around the risks associated with construction and will include seeking a major strategic partner for the project," Fraser said.