• Australian gold miner St Barbara cutting production forecast not unexpected, say Macquarie analysts

• Gold miner cuts FY25 production forecast to between 55,000 ounces and 65,000 ounces, from between 65,000 and 75,000 ounces

• SBM cites lower-than-expected average mining grade at Simberi operations in Papua New Guinea for forecast cut

• Raises forecast for all-in sustaining costs (AISC) to A$3,900 to A$4,200 per ounce, from A$3,200 to A$3,600 per ounce

• Macquarie says it was already forecasting a miss on SBM's prior FY25 guidance figures

• Brokerage hikes AISC estimate by 6% to align with SBM's revised guidance; maintains FY25 production guidance at 60,000 ounces

• SBM ends Tuesday down 6.8% at A$0.21

• Stock down 10% YTD, including current session's moves

(Reporting by Manasi Dasa in Bengaluru)