UK's Niox down 22 percent after halting private sale process
** Shares of medical devices group Niox NIOX.L tumbles 21.9% at 55.04 pence - lowest since July 2023 ** Stock set to record its worst day since June 2016 ** Co discontinues private sale process, viewing it as non-optimal for shareholders at present ** Keensight confirms it does not intend to make a firm offer for Niox due to the current macro-economic backdrop ** NIOX up 11.8% YTD (Reporting by Judes Joseph in Bengaluru) ((judes.joseph@thomsonreuters.com;))