The news follows the decision by the International Olympic Committee (IOC) to proceed with the postponed 2020 Olympics despite Covid-19 restrictions.
However, the committee took out around $800m (£568m) in event-cancellation insurance, with additional cover purchased by the local organising committee.
This included broadcasters, sponsors, professional sports teams and hospitality which the analysis has estimated would cost insurers if the event was cancelled between $2-$3bn (£1.4-£2.1bn)
Charles Graham, senior industry analyst, Bloomberg Intelligence, said: “Insurers and reinsurers will be on tenterhooks over the next six weeks as the Tokyo Olympics’ opening nears.
“Any cancellation of the already postponed 2020 event potentially costs the sector $2-$3bn in aggregate, based on our calculations. That would hit an event-cancellation industry already battered by record 2020 claims.”