** Office space supplier Regus +3.9%, among top FTSE250 gainers in decent volume
** RBC Capital Markets - rated at 5 stars for recommendationaccuracy on Regus, per StarMine - upgrades stock to "outperform"v "sector perform"
** Cites co's unrivaled market position, significantexpansion potential and strong structural growth drivers
** Stock -6% from end-March peak until Tues close (RM: tricia.wright1.thomsonreuters.com@reuters.net)
