** Shares of Zip Co ZIP.AX fall as much as 36.2% to A$1.80, set for their weakest trading session since November 14, 2014

** Stock hits lowest level since May 12, 2025

** Buy now, pay later services provider posted a drop in HY revenue margin to 7.9% vs 8.2% in pcp

** Co said it will only consider undertaking a dual listing in the U.S. when in best interests of shareholders

** Citi says core NAT of A$52 mln ($36.60 mln) an 11% miss vs VA consensus estimates

** Sandstone Insights of the opinion co chasing growth too aggressively, "will need to be closely monitored"

** Stock down 44.7% YTD, including the day's moves

($1 = 1.4207 Australian dollars)

(Reporting by Shivangi Lahiri in Bengaluru)

((shivangi.lahiri@thomsonreuters.com))