** Australia's top 20 firms' index .ATLI falls 1.8% to its lowest since August 5, 2024

** ATLI shed as much as 2.2% to its lowest since May 31, 2024, down ~11% since all-time high hit on February 14

** Decline in line with 1.6% drop in ASX200 index .AXJO over worries about impact of U.S. tariffs

** Top lender CBA CBA.AX falls 1.6%, extending losses to sixth consecutive session

** CBA lost ~A$37 bln ($23.26 bln) in value since mid-February

** National Australia Bank NAB.AX slumps 2.7%, trading near 11-month low

** Miners BHP BHP.AX and Rio Tinto RIO.AX drop ~1.6% each; Fortescue FMG.AX slips 0.3% after sliding as much as 2.4% earlier in the day

** Woolworths WOW.AX hits near six-year low; smaller rival Coles COL.AX falls 0.6%

** Data centre landlord Goodman Group GMG.AX set to finish at one-year low

** Biotech giant CSL CSL.AX dips 0.9%, hovers near 16-month lows

($1 = A$1.5906)

(Reporting by Sameer Manekar in Bengaluru)

((Sameer.Manekar@thomsonreuters.com;))