Feb 4 (Reuters) - Insurer Allstate's ALL.N fourth-quarter profit more than doubled on Wednesday, driven by strength in its property-liability business and higher investment returns.

Underwriting performance has strengthened across the sector, with catastrophe losses retreating from peaks that had weighed on the property and casualty insurance industry's profits over the past few years.

Income from underwriting at its property-liability business more than doubled to $4.01 billion in the quarter, compared with $1.83 billion a year earlier. Premiums written in the segment climbed 5.9%.

The segment reported an underlying combined ratio of 76.6%, compared with 83% a year earlier. A ratio below 100% indicates the insurer earned more in premiums than it paid out in claims.

Meanwhile, its net investment income rose to $892 million in the reported quarter, from $833 million a year earlier.

Insurers typically invest a portion of their capital in a mix of assets such as bonds and equities, with returns often tracking broader market movements.

The results echo fourth-quarter earnings trends at other major insurers. Chubb CB.BN and Travelers TRV.N both posted quarterly profits that exceeded Wall Street expectations by wide margins.

Analysts said the results reflect the “all-weather” nature of the insurance business, which remains resilient even as economic conditions weaken.

The insurer's profit was $14.37 per share in three months ended December 31, compared with $7.07 per share a year earlier.

(Reporting by Ateev Bhandari and Manya Saini in Bengaluru; Editing by Krishna Chandra Eluri)

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