** Shares of British advertising firm WPP WPP.L up in early trade but reversed course to fall 3.3% to 263.4 by 0807 GMT
** Co to merge its ad agencies into a single company
** CEO says she would also consider selling some assets
** WPP forecasts LFL revenue, less pass-through costs, to decline in the mid to high-single digits in H1 of 2026, with an improving trajectory in the second half
** 2025 revenue, less pass-through costs, fell 10.4% to 10.18 billion pounds ($13.79 billion), with headline operating profit down 22.6% to 1.32 billion pounds
** WPP has fallen about 18% so far this year
($1 = 0.7382 pounds)
(Reporting by Yamini Kalia in Bengaluru)
((Yamini.Kalia@thomsonreuters.com))