Liberty Mutual's net income slid 6.5% to $US425 million ($471 million) for the final three months of last year, despite a 15% jump in revenue to $US6.93 billion ($7.63 billion).

The US property and casualty insurer's net written premiums were up 12%, to $US5.58 billion ($6.18 billion).

A combination of catastrophes and net incurred losses attributable to prior years led Liberty Mutual's combined ratio down by 2.9 percentage points to 101%, meaning the insurer is no longer making an underwriting profit.

For the full year, Liberty Mutual's net income was down 6.6% to $US1.52 billion ($1.28 billion). Revenue was up 10% to $US25.96 billion ($28.75 billion), while net written premiums rose 9% to $US22.54 billion ($24.96 billion). The overall combined ratio for last year was 100.3%, a rise of one percentage point.