** Shares of GTN GTN.AX rise as much as 15.4% to A$0.525, their highest since April 3, 2023
** Stock posts its biggest intraday gain since Oct. 11, 2023
** Traffic information supplier says it intends to reinstate its share buy-back of up to 16 mln shares
** Says it is considering a one-off return of capital or special dividend
** About 761,000 shares change hands, compared with the 30-day average volume of around 331,000
** Stock up 5.1% YTD, including the session's move
(Reporting by Aaditya Govind Rao in Bengaluru)
((Aaditya.govindrao@thomsonreuters.com;))