The investigation is looking into the Carlauren Group that owned luxury care homes before going into administration in November 2019.
The SFO said the collapse left elderly residents forced to find somewhere else to live, with 600 investors also out of pocket.
The Carlauren Group bought 23 properties across the UK to turn into luxury care homes. The properties included former hotels, including the historic Windlestone Hall in Durham.
But the SFO claimed only nine of these became operational, with some continuing as hotels instead of care homes.
The group also allegedly bought a number of expensive cars, including two Lamborghinis and a McLaren 570GT. The group were also said to have purchased a private jet and two yachts.
Nick Ephgrave QPM, director of the Serious Fraud Office, said: "This company's abrupt collapse has created turmoil and enormous anxiety for many, with elderly people forced to vacate their homes and investors left with nothing.
"Today's arrests are a major development in our investigation and a step towards getting the answers so many people need."
According to reports, the Carlauren Group had around 600 investors through the purchase of rooms that were to be rented out to the elderly.
The luxury accommodation boasted swimming pools, room service and other amenities.
According to the SFO, the rooms were advertised and sold with a guaranteed annual payout and opportunity to sell the asset back for a profit after 10 years.
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