** Shares of Australia's Whitehaven Coal WHC.AX fall as much as 4.2% to A$6.16, their lowest level since July 21
** Stock marks weakest trading session since July 28
** Coal miner posts 57% drop in annual underlying NPAT from lower realised prices and higher cost of sales
** Declares final dividend of 6 Australian cents per share, less than half the 13 cents it paid out last year
** Stock last down 2.2%, trimming YTD gains to 1.5%
(Reporting by Sneha Kumar in Bengaluru)
((Sneha.kumar@thomsonreuters.com))