** Impax Asset Management Group IPX.L plunges as much as 20% to 121p, lowest since September 2017; among top pct losers across London
** British investment manager forecasts FY profit below market estimates, hurt by 26% fall in managed assets as of March-end and impact of escalating trade war
** CEO Ian Simm says, "Market conditions in the second half of FY25 remain highly uncertain"
** Co says net inflows affected after St. James's Place SJP.L terminated a 5.1 bln-pound ($6.5 bln) mandate and closure of small number of accounts within its institutional channel
** IPX last down 17.5%, taking YTD losses to ~50%
($1 = 0.7823 pounds)
(Reporting by Aby Jose Koilparambil in Bengaluru)
((abyjose.koilparambil@thomsonreuters.com))