** Shares of Appen APX.AX fall as much as nearly 15% to A$0.93, their lowest level since May 12

** AI co posts Q2 revenue of A$51.9 million ($33.86 million), a 6% drop from a year ago

** Co says that revenue is tracking towards the low end of the FY revenue guidance range of A$235 million - A$260 million

** Flags impact from short-term volatility due to "the dynamic nature of the U.S. AI market"

** YTD, shares down 64.1%

($1 = 1.5326 Australian dollars)

(Reporting by Nichiket Sunil in Bengaluru)

((Nichiket.Sunil@thomsonreuters.com))