SEOUL, Jan 29 (Reuters) - Hyundai Motor on Thursday reported a 40% fall in fourth-quarter operating profit versus a year earlier, as U.S. tariffs offset the positive impact of a weaker South Korean currency.

Hyundai, which together with affiliate Kia is the world's third-biggest automaking group by sales, booked operating profit of 1.7 trillion won ($1.19 billion) for October-December, compared with 2.8 trillion won in the same period a year earlier.

The result compared with a 2.7 trillion won LSEG SmartEstimate drawn from 17 analysts. The consensus estimate gives more weight to analysts who are more consistently accurate.

($1 = 1,426.2900 won)

(Reporting by Hyunjoo Jin and Heekyong Yang; Editing by Christopher Cushing)