2 Gulliver grads and dad sentenced to prison in MasTec insider trading case in Miami
More than 100 family members and supporters crammed into a Miami federal courtroom on Monday to witness the reckoning of a son, a father and a friend.
All three had pleaded guilty to insider trading that yielded more than $1 million in illicit profits off a corporate acquisition by one of South Florida’s biggest publicly held companies, MasTec.
Nearly four hours later, Federico Nannini, 26, Mauro Nannini, 64, and Alejandro Thermiotis, 26 — described by a federal judge as products of “privilege” — were respectively sentenced to six months, three months and five months in prison. Federico and Alejandro are graduates of Gulliver Preparatory, the exclusive private school in Pinecrest.
Although federal prosecutors sought more prison time for the defendants, U.S. District Judge Rodolfo Ruiz said he was trying to “strike a balance” between “appropriate” punishment in the securities fraud conspiracy and sending a message to South Florida’s investment community.
“They both completely lost it,” Ruiz said of Federico and Thermiotis, adding that the former Gulliver classmates’ financial crime involving text messaging was both “boneheaded” and “careless.”
The judge also said the father, Mauro Nannini, a former stock broker from Venezuela who owns a $7 million home in Coral Gables, “should have stopped it” by telling his son that insider trading on confidential information in MasTec’s purchase of another company was against the law.
Ruiz ordered all three men to pay restitution, including legal fees, to Federico’s former employer, Berkeley Research Group, a financial consulting firm in Miami that handled the MasTec deal with an Indiana company. Court records show Federico Nannini was ordered to pay his ex-employer $172,586; Mauro Nannini, $153,706; and Thermiotis, $153,706. The feds did not name the firm.
More than $1 million clawed back
Thermiotis, who made the bulk of the profits on the MasTec deal, cooperated with authorities against the father and son and was ordered to pay back his ill-gotten gains. His forfeiture judgment was $931,820.
Mauro Nannini’s forfeiture judgment was $180,328.
His son provided the confidential information on the MasTec deal to him and Thermiotis, but did not make any money off insider trades.
The three men, who apologized to the judge, family members and supporters, must surrender to prison authorities on July 1.
‘I made a great mistake’
“My dream was always to go into a career in finance,” Federico, who attended Bentley and Georgetown universities, said at Monday’s hearing, as he choked up and cried. “But then I made a terrible decision that I will regret for the rest of my life. ... The day I got arrested was the lowest point of my life.”
His father, Mauro, a retired developer, told the judge: “I made a great mistake, one that cost my family immense pain and shame.”
Thermiotis also showed remorse: “I’m sorry we’re all here.”
In September, the three men — along with another former Gulliver classmate, Francisco Tonarely, 25 — were charged with one count of conspiracy to commit securities fraud and 24 related offenses in a grand jury indictment. The Securities and Exchange Commission also filed a parallel civil lawsuit against them in Miami federal court.
In January, Tonarely ended up in a pre-trial diversion program for 12 months with no conviction in a rare deal with prosecutors at the U.S. Attorney’s Office. He made a minimal amount of money on the insider trading, according to his defense attorneys, Jeffrey Cox and James Sallah.
At the end of Monday’s hearing, Assistant U.S. Attorneys Elizabeth Young, Eli Rubin and Alexandra Comolli dropped the remaining counts in the case, which was investigated by the FBI. They struck plea deals with the Nanninis’ defense lawyers, Howard Srebnick and Jacqueline Perczek, as well as with Thermiotis’ attorneys, Michael R. Band and Michael Nadler.
How the scheme went down
According to the indictment and SEC case, here’s how the alleged scheme unfolded:
In June 2022, Federico Nannini, a consultant, began advising Coral Gables-based MasTec on its planned acquisition of Indiana-based Infrastructure and Energy Alternatives. MasTec, founded by the late Cuban exile Jorge Mas Canosa, is an engineering and construction company that provides infrastructure services for the energy, utility and communications industries.
At the time, both MasTec and Infrastructure and Energy Alternatives were traded on the NASDAQ.
Federico started sharing the confidential information with his father Mauro and his Gulliver pal Thermiotis, according to the indictment.
Mauro bought shares in the Indiana company the day after his son got access to the financial information about the proposed MasTec acquisition, the indictment says. Thermiotis also passed along the insider information about the deal to Tonarely.
In a text, Tonarely wrote Thermiotis: “I want to make some money right now. ... What [do] we do?”
After sharing the confidential information, Thermiotis texted him: “Not a soul okay.”
Tonarely responded: “Obviously. ... You told me not to.”
Days later, a member of Tonarely’s family signed a letter sponsoring Thermiotis’ membership at a Miami yacht club, prosecutors noted in a news release.
As the MasTec acquisition progressed, Federico continued to update his father and Thermiotis, about the deal. In turn, Thermiotis continued to share the insider information with Tonarely, prosecutors said.
In July 2022, Federico started worrying that the acquisition would fall through and confided in his father. Mauro sold his stock in Infrastructure and Energy Alternatives, the indictment says.
But when Federico saw confidential financial paperwork saying the deal was happening after all, he texted his friend, Thermiotis: “It’s going thru. ... Holy s--- bro.”
Thermiotis’ response: “Don’t text. ... But lfg.” Lfg means “let’s f---ing go.”
With that encouraging insider information, Mauro began to buy back his position in Infrastructure and Energy Alternatives, according to the indictment.
Toward the end of July, when MasTec’s acquisition of Infrastructure and Energy Alternatives was publicly announced, Mauro, Thermiotis and Tonarely sold their shares and options in the Indiana company for a profit, according to the indictment.
A couple of days later, on July 27, 2022, Federico texted Thermiotis a picture of a Rolex Daytona with the message: “You wanna hook it up for the boy. I know it’s a little over budget but this is the one.”
Thermiotis responded: “Haahaha yeah but give it a bit. ... Prices should come down a bit on everything.”
This story was originally published March 31, 2025 at 2:36 PM.
