* Focus turns to RBA's updated economic forecasts on Friday
* Origin Energy tops ASX200 losses on forecast cut
* AGL Energy slumps 3.6% on flagging impairment charge
* NZ50 closes at two-week low (Updates to close)
Feb 4 (Reuters) - Australian shares snapped a three-day winning streak to close lower on Thursday, as healthcare and gold stocks declined, while power retailer Origin Energy was the biggest loser on the index after slashing outlook for its energy markets division.
The S&P/ASX 200 index .AXJO ended 0.9% lower at 6,765.5.
Investors' focus shifts to comments from the Reserve Bank of Australia (RBA), slated to provide updated economic forecasts on Friday, after announcing earlier this week it would expand its bond-buying programme by another A$100 billion. retailer Origin Energy ORG.AX dropped 6.9% to a three-month low after downgrading the fiscal 2021 outlook for its energy markets division. country's top power producer AGL Energy AGL.AX slumped 3.6% after saying it expected to book a A$2.69 billion charge in its half-year results to write down the value of its assets and previously signed wind energy contracts. .AXMM lost 0.5%, with world's largest miner BHP BHP.AX falling 0.5%.
Gold stocks .AXGD slid 2.8% to hit their lowest in nine months after bullion prices eased overnight. Newcrest Mining NCM.AX shed 2.2% and Ramelius Resources RMS.AX plunged to a near-nine-month low.
Healthcare stocks .AXHJ also declined, with sector heavyweight CSL CSL.AX shedding 1.8%.
New Zealand's benchmark S&P/NZX 50 index .NZ50 ended 0.8% lower at 12,992.14, with eight out of nine sectors closing in the red.
Telecom services provider Chorus Ltd CNU.NZ fell 3.8% to be the top loser on the benchmark.