** Online hostel booking platform Hostelworld's shares HSW.L fall over 9% to 128.5p - among top pct losers in FTSE small cap index .FTSC
** Posts ~23% fall in H1 adj. EBITDA to 7.4 million euros ($8.7 million) due to higher marketing costs in first few months of H1, which have since moderated
** Expects FY adj. EBITDA in line with market expectations of 19.9 million euros, according to company-compiled poll
** YTD, HSW stock down 9%
($1 = 0.8527 euros)
(Reporting by Unnamalai L in Bengaluru)
((Unnamalai.L@thomsonreuters.com;))