Manchester City have been found guilty of all but one of 115 Premier League charges they face for breaching financial regulations, the Athletic reported on Friday.
The report added that no sanction had yet been decided and that City are set to appeal.
The outcome of an independent hearing that began more than two years ago could send shock waves through English football.
The legacy of City's trophy-laden era is on the line over accusations it had been built on financial impropriety.
City were charged by the Premier League in 2023 following an investigation into alleged breaches between 2009 and 2018.
The club, who have always denied the allegations, were accused of failing to provide accurate financial information and details of payments to players and coaches, as well as breaches of financial sustainability rules.
Under the ownership of Sheikh Mansour, whose Abu Dhabi United Group acquired the club in 2008, City have become the dominant force in English football.
They have won eight Premier League titles, four FA Cups, seven League Cups and one Champions League in the past 15 years.
The root of suspicion came from leaked documents published by German outlet Der Spiegel back in 2018.
Emails purportedly sent between top City executives showed the club had inflated sponsorship revenue from Abu Dhabi state-controlled airline Etihad and telecoms firm Etisalat by disguising direct investment from Mansour’s Abu Dhabi United Group as income.
Other documents claimed to show off-the-books payments to then manager Roberto Mancini via consultancy fees from a club in Abu Dhabi.
If City are found guilty, sanctions are likely to include a severe points deduction and possibly even expulsion from the Premier League.
Everton and Nottingham Forest were both hit by points deductions in the 2023/24 season for single breaches of profit and sustainability rules.
A severe punishment would also raise doubts over the future of City's cast of star players, including prolific striker Erling Haaland.
Other clubs could make a claim for titles to be stripped and compensation if City gained an unfair advantage by nefarious means.