The young Dane arrived in January from Lecce, becoming the latest gem uncovered by the Serie A club's famed sports director Pantaelo Corvino.
Speaking at this week's Business of Football Summit, Trimboli said: “Corvino who has a long tradition of buying players cheap, developing them and then selling on for substantial profits.
“In his mind he’d done the research and seen what was out there, understood that January is one of those windows where if you have an asset and have to sell, there’s a premium attached - because it is the worst time to sell.”
Trimboli added: “They knew what previous players have been sold for and started with that number.
“Then it came down to market forces, supply and demand.
“United knew what they wanted to pay. Lecce knew what they wanted to receive.
“There was a bit of brinkmanship that came into play but eventually they got there.”
United manager Ruben Amorim has been quick to introduce the youngster to the first team, though he was sent off in the win at Ipswich last month.