Marshall, the hedge fund tycoon who already owns the UnHerd website, is also in the running to buy the Daily and Sunday Telegraph, with the second round of bids by prospective buyers due by 27 September.
The tycoon, a backer of the GB News television channel, which launched three years ago, has acquired the politically conservative magazine through his Old Queen Street Ventures (OQS).
Marshall, who has been in exclusive talks to buy the world's longest-running weekly magazine for the past month, has promised to keep the Spectator an independent part of his rapidly expanding British media empire.
Marshall, who will house the Spectator within the subsidiary Old Queen Street Media alongside UnHerd, said he is "confident that OQS will be a fine custodian".
"The plan is for OQS to make good previous underinvestment in one of the world's great titles," he said.
Freddie Sayers, the chief executive of OQS, will become the publisher of both titles. He said the Spectator would remain separate, with independent editorial and governance structures, including a new board likely to include Tory politicians.
This story is from the {{IssueName}} edition of {{MagazineName}}.
Start your 7-day Magzter GOLD free trial to access thousands of curated premium stories, and 9,000+ magazines and newspapers.
Already a subscriber ? Sign In
This story is from the {{IssueName}} edition of {{MagazineName}}.
Start your 7-day Magzter GOLD free trial to access thousands of curated premium stories, and 9,000+ magazines and newspapers.
Already a subscriber? Sign In
First mass 24-hour event to help people put down their phones
Haunted by a pile of unread books? Or taunted by outdoor kit lurking in the cupboard? If you are one of the British adults who spends on average five hours a day looking at screens rather than participating in pastimes, perhaps it's time to join the offline revolution.
No longer the king of bling The staggering fall of rap star Sean 'Diddy' Combs
Brooklyn's grim Metropolitan Detention Center is, for the foreseeable future, home to Puff Daddy, AKA Sean Combs, one of the best-known voices in American entertainment and whose business empire once seemed to know no bounds.
Brandenburg stakes Last-minute push by German far right in key regional election
B jörn Höcke shielded his eyes from the lights as he peered from the stage into the crowds gathered on a square in front of a gothic church in central Cottbus.
'It's guerrilla war' The fire teams facing arson chaos in Amazon
The occupants of the military tents at this remote jungle camp in Brazil's wild west T survey the hellscape surrounding them.
"The horror of it' Trial of husband and 50 men accused of wife's rape shakes France
On the narrow streets of stone houses with pastel-blue shutters, residents of Mazan were appalled that this picturesque village in Provence was being referred to in the media as \"the village of the rapists\".
West End revival Will a traffic ban lure shoppers back to Oxford Street?
From the rooftop of John Lewis's flagship store, the London mayor, Sadiq Khan, laid out the changes planned for Oxford Street below: \"We want a public realm that is world class, green, healthy and safe but also increases footfall in the shops.\"
Live and let fly James Bond chopper firm awaits decision on £1bn deal
The Merlin helicopter sitting on a factory floor in Yeovil is a sight familiar to James Bond aficionados from the climactic shootout of the 2012 film Skyfall.
Mental illness is Britons' biggest health concern, survey finds
Mental health has overtaken cancer and obesity as the health issue that is the biggest cause of concern for most Britons, a global survey reveals.
Noise, crime, crowds Rise in tourism stokes tensions in bustling Lake District town
Even on a weekday afternoon at the very tail end of summer, Bowness-onWindermere is bustling with life. Outside the town's pubs and bars, drinkers sip lager and sparkling wine in the warm September sun.
EU's new proposals on youth mobility will put Starmer 'reset' to test
Fresh proposals to allow young people to move between Britain and the EU will be presented to the British government within weeks, in what is seen as a significant early test of Labour's \"reset\" in relations with Brussels.
