* Aussie shares could fall for a sixth straight day
* Financials biggest drag on benchmark
* Aristocrat Leisure leads gains on solid 1H
* a2 Milk rally boosts New Zealand
By Aditya Soni
May 24 (Reuters) - Australian shares edged down on Thursday, with banks leading the way lower.
The S&P/ASX 200 index .AXJO , which has lost ground the past five sessions, was down 9.50 points, or 0.2 percent, to 6023.0 at 0324 GMT. The benchmark declined 0.2 percent on Wednesday.
Thursday's biggest gainer was gambling equipment maker Aristocrat Leisure ALL.AX , which reported a solid rise in first-half profit.
The financial index .AXFJ , which has also declined five straight days, dipped 0.9 percent to a near four-week low.
"The ongoing Royal Commission enquiry into the sector is clearly having an impact," said Michael McCarthy, chief market strategist at CMC Markets.
Financials have lost more than 1 percent since the third round of Australia's inquiry into the industry began on Monday.
Australia and New Zealand Banking Group Ltd ANZ.AX slipped 0.9 percent to its lowest since May 14 and National Australia Bank Ltd NAB.AX slid as much as 1.3 percent.
An Australian court on Thursday rejected the regulator's rate-rigging case against Westpac Banking Corp WBC.AX . said with the clearance for the manipulation charge and the expected penalties, the impact on the bank's bottom line should be small.
Shares of the second-biggest lender were 1 percent lower.
Material stocks on Thursday also had losses, due to overnight weakness in iron ore and copper prices. IRONORE/ MET/L
Global miner Rio Tinto (LON:RIO) Ltd RIO.AX dipped 0.7 percent, while Fortescue Metals Group Ltd FMG.AX dropped as much as 1.5 percent to its lowest since April 30.
A fall in oil prices led to weakness in energy stocks, with Woodside Petroleum Ltd WPL.AX dropping 1 percent, while Oil Search Ltd OSH.AX declined as much as 1.7 percent to a two-week low.
Aristocrat Leisure Ltd surged 8.1 percent to its highest ever level. It said net profit for the half ended March 31 rose 2.8 percent as digital revenue more than tripled. staples were also higher, propped up by gains in Australia-listed shares of A2 Milk Company Ltd A2M.AX , which rose 6.8 percent, their biggest intraday percentage advance in more than three months.
In New Zealand, the benchmark S&P/NZX 50 index .NZ50 rose 0.7 percent or 61.50 points to 8,614.73.
Dairy firm a2 Milk Company Ltd ATM.NZ accounted for most of the gains, rising as much as 6.5 percent to its highest since May 22. The stock lost nearly 14 percent the past four-days.