Shares of Loews Corp. (L) - Get Report   fell 6.1% to close at $44.56 Monday after it swung to a fourth-quarter loss of $165 million.

A year earlier the New York-based insurer reported a profit of $481 million. On an adjusted basis, the company reported earnings in the fourth quarter of 36 cents per share on revenue of $3.29 billion, down 7.5% from a year ago.

The company said the loss was driven by "catastrophe losses at CNA Financial Corp.," but the company also said that the discrepancy between this quarter's earnings and last year's was due partly to the $200 million benefit booked in the 2017 fourth quarter thanks to the Tax Cuts and Jobs Act of 2017. 

Loews said total expenses in the quarter increased 13.7% year over year to $3.5 billion. 

For the year, thanks in part to the tax reform benefit, the company's earnings jumped 42.3% to $1.99 a share while revenue rose 2.4% year over year to $14.1 billion.