UPDATE 2-Travelers 4th-qtr profit beats on premium growth; shares jump

(Adds details, updates share price)

Jan 23 (Reuters) - Property and casualty insurer Travelers Cos Inc core adjusted fourth-quarter earnings beat Wall Street expectations as growth in premiums offset a rough period for catastrophe losses from California wildfires, it said on Tuesday.

Travelers, like other companies in the sector this quarter, swallowed a $129 million charge related to the new U.S. tax law, which contributed to its net income falling 42 percent to $551 million, or $1.98 per share, from $943 million, or $3.28 per share, a year earlier.

Shares of the New York-based Travelers, a component of the Dow Jones industrial average, jumped 4 percent at $144.98 in late-morning trading.

"There has been a lot of speculation about how corporate tax reform will impact pricing," said Travelers Chairman and Chief executive Officer Alan Schnitzer in prepared remarks during a conference call with analysts. "Tax reform helps but we still have ground to cover."

The tax rate is just one factor affecting premium prices necessary to reach the company's financial goals, Schnitzer said, along with expenses and insured losses.

On an adjusted basis, Travelers earned $2.28 per share, handily beating the average analyst estimate of $1.51, according to Thomson Reuters I/B/E/S.

Net written premiums in the quarter rose 6 percent to $6.42 billion.

Travelers' pretax catastrophe losses, net of reinsurance, more than tripled to $499 million from $137 million a year earlier, as a result of the California wildfires.

The figure was lower than the forecast range of $525 million to $675 million.

California wildfires in 2017 were the most destructive and deadliest in the state's history, wrecking more than 21,000 homes and 2,800 businesses.

Catastrophe losses in the quarter weighed on the insurer's underwriting gains, which slumped 45 percent to $216 million.

As a result, its combined ratio, which measures an insurer's profitability, worsened to 95.5 percent from 90 percent a year ago. A ratio below 100 percent indicates the insurer earns more in premiums than it pays out in claims and expenses.

Despite rising interest rates, net investment income fell 5.3 percent to $467 million.

Travelers' revenue rose 3.6 percent to $7.45 billion. (Reporting by Nikhil Subba in Bengaluru and Suzanne Barlyn in New York; Editing by Arun Koyyur and Jeffrey Benkoe)