The probe will focus on the audit of the financial statements of ISG Limited for the year ended 31 December 2022 conducted by MacIntyre Hudson LLP.
The investigation will be conducted by the FRC’s Enforcement Division under the Audit Enforcement Procedure.
The £2.2bn turnover ISG group went into administration last September with debts of £1.1bn including more than £308m owed to trade contractors.
Results for the year to 31 December 2022 were the last published by ISG before its collapse.
Its accounts for 2023 were overdue and never published but expected to contain £148m in contract write downs and a £133m pre-tax loss.