A Milan court on Tuesday convicted Lazio Chairman Claudio Lotito of share-rigging and obstructing bourse oversight bodies.
Lotito received a two-year jail term and a 65,000-euro fine and was banned from holding public office for a year.
The jail sentence, which is automatically suspended pending appeal, was four months longer than prosecutors had requested. The fine was 45,000 euros higher.
The Roman club's second-biggest shareholder, Roberto Mezzaroma, was convicted of the same offences and received an 18-month term, two months longer than requested.
Mezzaroma, who also received a one-year ban from public office, was fined 55,000 euros, 35,000 more than prosecutors had asked.
The pair's lawyers voiced confidence their clients would be cleared on appeal and that the trial would be moved to its ''natural venue'' in Rome.
The Milan judges twice rejected a defence plea to transfer the proceedings to Rome.
Prosecutors successfully argued that the pair formed an illicit syndicate to keep control of the Roman club.
In the investigation, police searched the homes of both men as well as the offices of Lazio, two of its creditor banks, Capitalia and Unicredit, and other firms linked to Lotito.
In Milan, prosecutors probed share-price rigging.
Lotito was accused of getting his business partner Mezzaroma to secretly acquire a 14.6% slice of the club so the chairman could fend off any challenge to his ownership thanks to a 30%-plus share.
By Italian law, a shareholder who goes over the 30% threshold is obliged to launch an initial public offering (IPO) - something which Lotito avoided through his secret pact with Mezzaroma, the prosecutors said.
Lazio, Rome's second club along with AS Roma, enjoyed a spell of success under big-spending business magnate Sergio Cragnotti in the late 1990s and won the scudetto in 2000.
Cragnotti fell from grace in a bankruptcy scandal and the club was taken over by Lotito who last year took it back into the Champions League despite operating on an austerity budget including wage and transfer caps.
The club is currently 8th in Serie A, two places behind Roma which has outperformed it in the last two years, finishing runners-up behind Inter Milan.
In a separate case, allegedly involving ex-Lazio great Giorgio Chinaglia, the Neapolitan crime syndicate Camorra tried to buy the club in 2006 to use it for money laundering, police say.
