** Shares of Viva Energy VEA.AX fall as much as 5.6% to A$2.020, its biggest intraday pct fall since July 29
** Fuel retailer posts 67.4% drop in its HY net profit attributable on a replacement cost basis of A$62.6 million ($40.68 million)
** Co announces interim dividend of 2.8 Au cents per share as compared to an interim dividend of 6.7 Au cents apiece, declared last HY
** Stock has fallen 19.8% this year, as of 0502 GMT
($1 = 1.5389 Australian dollars)
(Reporting by Roshan Thomas in Bengaluru)
((Roshan.Thomas@thomsonreuters.com;))