** Shares of luxury goods retailer Cettire CTT.AX tumbles nearly 21% to A$0.2675, set for their weakest session since June 12
** Stock set for three consecutive sessions of losses
** U.S. halts "de minimis" exemption, which permitted low-value commercial shipments to enter the country tariff-free
** Co says it is assessing changes to U.S. tariffs
** Nearly 40% of co's May-June gross rev came from U.S. shipments, with low-value packages representing the majority
** Trading volume at 14 mln shares, 3.3x the 30-day avg
** YTD, stock has lost over 80%
(Reporting by Kumar Tanishk in Bengaluru)
((Tanishk.Kumar@thomsonreuters.com; X: @thatstanishk;))