** Shares of Santos STO.AX slip as much as 2.9% to A$7.770, on track for biggest intraday fall since August 20

** Australian energy company trades ex-dividend; to pay interim dividend of 13.4 US cents per share

** Santos among top decliners on broader energy stocks sub-index .AXEJ, which is down 0.8%

** STO last down 2.3%, bringing YTD gains to 17.1%

(Reporting by Keshav Singh Chundawat in Bengaluru)

((Keshav.SinghChundawat@thomsonreuters.com;))