Go Ahead Group (LSE:GOG) went sharply into reverse in early trading on Thursday after it said its shares were likely to be suspended in January because it cannot get its accounts done on time.
The group admits it breached the terms of its London & South Eastern Railway franchise contract with the Department for Transport, and faces a possible fine as a result.
It said: "Serious errors were made by LSER with respect to its engagement with the DfT over several years. In particular, the group accepts that, by failing to notify the DfT of certain overpayments or monies due to the DfT, LSER breached contractual obligations of good faith contained in the franchise agreements."
Services on the line were subsequently taken over by the government.
Go Ahead expects to make a provision for the fine in its 2021 accounts, but it needs more time to consider the implications of an independent report into the situation.
So its auditors will not complete the accounts by 3 January 2022, the latest date they can be published. So it expects it shares to be suspended the next day, until the results are released.
UK rail trading is ahead of expectations, but a material provision may be taken for potential losses in Norwegian rail and a provision for German rail will rise by £10mln.
Its shares slumped 23.58% or 166.25p to 538.75p.