Shares in Trainline PLC (LSE:TRN, FRA:2T9A), the rail and coach ticketing platform, fell 14% to 208.4p on Wednesday after the competition regulator opened an investigation into how it presents booking fees to customers.
The Competition and Markets Authority (CMA) is examining whether Trainline engaged in "drip pricing", where mandatory charges appear later in the buying process rather than in the headline price.
The watchdog is running parallel probes into Virgin Atlantic, over resort fees on package holidays, and RED Driving School, over booking and digital charges.
The CMA said it had observed transaction fees ranging from 59p to £2.79 on train bookings, plus a £1.50 fee on coach tickets, and was questioning whether these were shown in the upfront total.
It stressed the case was at an early stage and that it had reached no conclusions on whether the law had been broken.
If it finds an infringement, the regulator can order compensation for affected customers and impose fines of up to 10% of global turnover.
Both Panmure Liberum and Stifel, the brokers, kept buy ratings on the stock, though with sharply different price targets of 420p and 330p respectively.
Panmure Liberum questioned the timing, saying it was surprising the CMA had acted after the Office of Rail and Road, which regulates fee presentation in the sector, had already agreed changes with the companies involved.
The broker noted Trainline began showing booking fees on its ticket selection page in March 2025, before the CMA's new consumer powers took effect in April that year.
It added that Trainline's fees were no less clear than those of other platforms such as Deliveroo, which also fold charges into the first basket total shown.
Where the CMA rules against a company, Panmure Liberum said there was precedent for fines and for repayment of booking fees charged since the powers came into force.
Stifel took a similar view, arguing the investigation would weigh on the shares until it was resolved, even though it expected any operational impact to be short-lived.
The broker said Trainline planned to roll out further changes to fee presentation in the near term, but warned that government timelines made the outcome hard to predict.
Neither broker changed its earnings forecasts.
Trainline had earlier received an advisory letter from the CMA over its pricing, and the regulator escalated to a formal investigation after continued monitoring left it concerned.
