Trainline shares slump as the ticket firm sets aside nearly £4m over a watchdog probe into its pricing tactics

The Competition and Markets Authority launched its investigation into Trainline, Virgin Atlantic and Red Driving School in August over suspected drip-pricing, where extra fees are added during checkout.

The CMA is examining whether the companies misled customers by hiding mandatory charges until late in the booking process.

Trainline's share price fell sharply on the dual blow of weaker profits and the regulatory overhang from the watchdog investigation.