v3.25.2
RESERVE FOR LOSSES AND LOSS EXPENSES
 6 Months Ended
Jun. 30, 2025
Insurance [Abstract]  
RESERVE FOR LOSSES AND LOSS EXPENSES RESERVE FOR LOSSES AND LOSS EXPENSES
Reserve Roll-Forward

The following table presents a reconciliation of the Company's beginning and ending gross reserve for losses and loss expenses and net reserve for unpaid losses and loss expenses:
Six months ended June 30,
20252024
Gross reserve for losses and loss expenses, beginning of period$17,218,929 $16,434,018 
Less reinsurance recoverable on unpaid losses and loss expenses, beginning of period(6,840,897)(6,323,083)
Net reserve for unpaid losses and loss expenses, beginning of period10,378,032 10,110,935 
Net incurred losses and loss expenses related to:
Current year1,625,845 1,494,659 
Prior years(38,166)— 
 1,587,679 1,494,659 
Net paid losses and loss expenses related to:
Current year(166,553)(159,455)
Prior years(1,395,871)(1,251,637)
 (1,562,424)(1,411,092)
Foreign exchange and other(1,611,164)(47,452)
Net reserve for unpaid losses and loss expenses, end of period8,792,123 10,147,050 
Reinsurance recoverable on unpaid losses and loss expenses, end of period9,086,900 6,591,821 
Gross reserve for losses and loss expenses, end of period$17,879,023 $16,738,871 
On April 24, 2025, the Company completed a loss portfolio transfer reinsurance agreement with Cavello Bay Reinsurance Limited, a wholly-owned subsidiary of Enstar Group Limited ("Enstar") which was deemed to have met the established criteria for retroactive reinsurance accounting (refer to Note 14 'Related Party Transactions'). At June 30, 2025, foreign exchange and other included an increase in reinsurance recoverable on unpaid losses of $2 billion related to this transaction.
At June 30, 2025, net reserves for losses and loss expenses included estimated amounts for numerous catastrophe events. The magnitude and complexity of losses arising from certain of these events inherently increase the level of uncertainty and, therefore, the level of management judgment involved in arriving at estimated net reserves for losses and loss expenses. These events include California Wildfires in 2025, Hurricane Milton and Hurricane Helene in 2024. As a result, actual losses for these events may ultimately differ materially from current estimates. During the six months ended June 30, 2025, the Company recognized catastrophe and weather-related losses, net of reinsurance, of $86 million (2024: $67 million).
Prior Year Reserve Development

The Company's net favorable (adverse) prior year reserve development arises from changes to estimates of losses and loss expenses related to loss events that occurred in previous calendar years. The following table presents net favorable (adverse) prior year reserve development by segment:
  Three months ended June 30,Six months ended June 30,
2025202420252024
Favorable (Adverse)Favorable (Adverse)Favorable (Adverse)Favorable (Adverse)
Insurance$15,216 $— $29,194 $— 
Reinsurance5,013 — 8,972 — 
Total$20,229 $— $38,166 $— 

The following sections provide further details on net favorable (adverse) prior year reserve development by segment, reserve class and accident year:

Insurance Segment:

The following table maps the Company's lines of business to reserve classes:
Insurance segment
Reserve class
Property
Casualty
Specialty other
Reported lines of business
PropertyX
Professional linesX
Liability
X
CyberX
Marine and aviation
X
Accident and healthX
Credit and political risk
X

Prior year reserve development by reserve class was as follows:
Three months ended June 30,Six months ended June 30,
2025202420252024
Favorable (Adverse)Favorable (Adverse)Favorable (Adverse)Favorable (Adverse)
Property
$6,980 $— $16,976 $8,011 
Casualty
— — — — 
Specialty other
8,236 — 12,218 (8,011)
Total$15,216 $— $29,194 $— 
2025
For the three months ended June 30, 2025, net favorable prior year reserve development of $15 million was recognized, the principal component of which was: 
•$7 million of net favorable prior year reserve development on property business primarily due to better than expected loss emergence mainly related to the 2023 accident year.
•$8 million of net favorable prior year reserve development on the specialty other reserve class primarily due to better than expected loss emergence attributable to the credit and political risk line of business.
2025
For the six months ended June 30, 2025, net favorable prior year reserve development of $29 million was recognized, the principal component of which was: 
•$17 million of net favorable prior year reserve development on property business primarily due to better than expected loss emergence mainly related to the 2023 accident year.
•$12 million of net favorable prior year reserve development on the specialty other reserve class primarily due to better than expected loss emergence attributable to the credit and political risk line of business related to several accident years.
2024
For the six months ended June 30, 2024, net prior year reserve development of $nil was recognized, the principal components of which were: 
•$8 million of net favorable prior year reserve development on property business primarily due to better than expected loss emergence mainly related to the 2021 and 2022 accident years.
•$8 million of net adverse prior year reserve development on the specialty other reserve class primarily due to an increase in the loss estimate attributable to a specific large claim in the marine and aviation line of business related to the 2019 accident year.
Reinsurance Segment:
The following table maps the Company's lines of business to reserve classes:
Reinsurance segment
Reserve class
Casualty
Specialty
Run-off
Reported lines of business
Liability
X
Professional lines
X
Motor
X
Accident and health
X
Credit and surety
X
Agriculture
X
Marine and aviation
X
Catastrophe
X
Property
X
Engineering
X
Prior year reserve development by reserve class was as follows:
  Three months ended June 30,Six months ended June 30,
  2025202420252024
Favorable
(Adverse)		Favorable
(Adverse)		Favorable
(Adverse)		Favorable
(Adverse)
Casualty
$— $— $— $— 
Specialty
5,013 — 8,847 — 
Run-off
— — 125 — 
Total$5,013 $— $8,972 $— 
2025
For the three months ended June 30, 2025, net favorable prior year reserve development of $5 million was recognized.
•$5 million of net favorable prior year reserve development on the specialty reserve class business.
2025
For the six months ended June 30, 2025, net favorable prior year reserve development of $9 million was recognized.
•$9 million of net favorable prior year reserve development on the specialty reserve class primarily due to better than expected loss emergence attributable to the agriculture line of business mainly related to the 2023 and 2024 accident years.