The body was pulled from the wreck on the fourth day of searches since the boat sank early on Monday morning.
This brought the confirmed death toll to six, with one person still missing.
The 56-metre British-flagged boat was anchored some 700 metres off Porticello, east of Palermo, when it was struck by a waterspout – akin to a mini-tornado.
It sank within minutes.
Fifteen people were rescued, including Lynch's wife Angela Bacares and a woman with a one-year-old baby. The body of a man, believed to be the yacht's chef, was found several hours later.
Four other bodies were recovered on Wednesday.
Italian media reports quoting sources from divers said Lynch's lawyer Chris Morvillo, his wife Neda Morvillo, Morgan Stanley International chair Jonathan Bloomer and his wife Judy Bloomer were the victims retrieved on Wednesday.
All the men missing after the sinking had been found, a coast guard official told AFP on Thursday.
Specialist divers were still looking for a missing woman, he added.
Lynch, an entrepreneur sometimes referred to as Britain's Bill Gates, had invited the guests onto the yacht to celebrate his recent acquittal in a US fraud case.
The 59-year-old was acquitted on all charges in a San Francisco court in June after he was accused of an $11-billion fraud linked to the sale of his software firm Autonomy to Hewlett-Packard.
Among the survivors was Charlotte Golunski, board director of a company founded by Lynch, who has described how she briefly lost hold of her one-year-old daughter before grabbing her again. Both were plucked to safety.
Fabio Genco, a member of the Palermo Emergency Medical Services who was among the emergency responders that treated the child, described the "apocalyptic" situation he found upon arriving at the scene.
"The word that the mother and all the injured kept repeating was 'darkness', the darkness that they experienced during the shipwreck," he told the BBC's Newsnight programme.
"They spoke of about five minutes, maybe from three to five minutes, from the moment the boat was lifted, raised by the waves of the sea, until it sank."
He said the survivors rescued had been in shock: "There were truly apocalyptic scenes where everyone was searching and hoping to find the people who at that moment, were not present or just missing."
All the survivors treated in hospital have been discharged, he confirmed.
The speed with which the yacht sank, and the fact that other boats around it were unaffected, was highly unusual, according to experts.
Despite eyewitness accounts that the 75-metre mast had snapped, reports on Wednesday suggested that it was intact.
Some key questions remain, including whether the keel, which provides a counterbalance to the towering mast, was down when the storm hit.
Italian authorities have opened an investigation into the incident and are interviewing all survivors, including captain James Cutfield, a 51-year-old New Zealander, according to Italian media.
The UK's marine accident investigation branch also sent four inspectors.
Matthew Schanck, from the Maritime Search and Rescue Council, told AFP what happened was "pretty unprecedented".
UK meteorologist Peter Inness described a waterspout as a "narrow column of rotating air below a thunderstorm that occurs over water".
Like tornadoes, they suck up air in a rotating motion. Many are fairly inconsequential, but some can pack winds of more than 100 kilometres per hour, Inness said.
Jean-Marie Dumon, a former naval officer now with the GICAN, the French maritime industry association, added that conditions with winds of 100kph or more can "create completely anarchic sea conditions which can cause capsizing".
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