* Benchmark gains 0.5% over the week
* All Big Four banks finish in red, lose between 6%-7.5%
* Woodside Petroleum slashes $2 bln in spending, slips over 6%
* NZ benchmark gains nearly 4% over the week (Updates to close)
March 27 (Reuters) - Australian shares slipped more than 5% on Friday, but managed to clock a marginal weekly gain, as sweeping quarantine rules to curb the spread of the coronavirus intensified fears of a deeper economic fallout despite stimulus measures.
The S&P/ASX 200 index .AXJO was unable to hold on to initial gains, and fell 5.3% to finish at 4,842.40. The index ended the week 0.5% higher, with Friday's losses erasing about most of the gains made over the past three sessions.
The index has fallen nearly 33% since its peak on Feb. 20.
Australia will be introducing enforced quarantine by midnight on Saturday for citizens returning home from overseas, as the number of coronavirus cases surpassed 3,000 on Friday from less than 100 at the start of March, raising fears of a community spread. Research estimates that "a six-week widespread shutdown in second-quarter and then a progressive relaxation will see gross domestic product slump 13% over the quarter."
Meanwhile, listed companies in Australia and New Zealand have already laid off or began considering laying off at least 106,955 people, temporarily or permanently, underlining the toll on livelihoods as virtual lockdowns take hold. rise in unemployment is mitigated to some extent by government policy and the expected temporary nature of the shutdown, but considerable job losses seem unavoidable, at least for a period," ANZ Research added in a note. It expects unemployment to be around 7% by the end of 2021.
Heavyweight financials sub-index .AXFJ declined 5.8%, with all the Big Four banks finishing firmly in the red.
Top lender Commonwealth Bank of Australia CBA.AX and second-largest bank Westpac Banking Corp WBC.AX declined 6.7% and 7.1%.
Among mining stocks .AXMM , which represent a majority chunk in the index, global miners BHP Group BHP.AX and Rio Tinto (LON:RIO) RIO.AX finished 5.4% and 2.7% lower, respectively.
Energy stocks .AXEJ shed more than 5%, with Woodside Petroleum WPL.AX losing 6.4% after it halved its forecast spending for 2020 and deferred go-ahead decisions for its two biggest gas projects. New Zealand, the benchmark S&P/NZX 50 index .NZ50 slipped 0.8% to finish at 9,556.73, snapping three straight sessions of gain. However, the index rose nearly 4% over this week after losing more than 19% over the previous two weeks.
On Friday, most blue-chip stocks weighed down the index, with NZ-listed shares of Westpac Banking Corp WBC.NZ losing 2.5%, and Auckland International Airport AIA.NZ shedding 4.6%.