GB Group PLC (LSE:GBG) shares fell 14.5% to 210p after the identity verification software company swung to a paper loss and unveiled plans to increase investment in its flagship platform, which will slightly squeeze profit margins in the coming year. The FTSE 250-listed group reported revenue up 3.2% on a constant currency basis to £285 million in the year to 31 March, while adjusted operating profit increased 0.7% to £67.5 million.