(Adds details from conference call, updates shares)
Feb 10 (Reuters) - Molson Coors Brewing Co reported a lower-than-expected quarterly profit as beer sales fell and marketing expenses rose, and said a strong dollar was likely to hurt profit in 2015.
Molson Coors shares fell as much as 6 percent after Chief Executive Mark Hunter also said the company did not expect U.S. operating margins to increase in 2015 due to higher spending on marketing.
The company's fourth-quarter net sales fell in all its markets for the first time in two years, despite boosting spending on marketing. Net income fell 31 percent.
MillerCoors LLC, the U.S. joint venture of Molson Coors and SABMiller Plc, reported a 10 percent fall in quarterly net profit on lower sales and higher marketing spending.
MillerCoors also said Chief Executive Tom Long will retire on June 30, and it was looking for a successor.
The company has been ramping up spending to boost falling sales of its brands including Miller Lite and Coors Light.
Sales of Miller Lite rose for the first time since 2007, increasing in the low single-digits in percentage terms in the fourth quarter.
MillerCoors had changed Miller Lite's label to the original one used in 1975, and has been running an ad campaign promoting the brand as the pioneer lower-calorie beer.
Molson Coors on Tuesday announced a $1 billion share repurchase plan over four years and raised its quarterly dividend to 41 cents per share from 37 cents.
Net income attributable to Molson Coors fell to $94.1 million, or 50 cents per share, from $137.2 million, or 74 cents per share, a year earlier.
Excluding items, the company earned 55 cents per share.
Net sales fell 5.5 percent to $973.8 million.
Analysts on average had expected earnings of 69 cents per share on revenue of $969.2 million, according to Thomson Reuters I/B/E/S.
Tax rate in the quarter was 24 percent, above the 14 percent estimated, which could have hurt per share profit by 6-7 cents, J.P. Morgan Securities analyst John Faucher wrote in a note.
Molson Coors shares were down 2.5 percent at $74.40 on the New York Stock Exchange on Tuesday. (Reporting by Sruthi Ramakrishnan in Bengaluru; Editing by Sriraj Kalluvila and Don Sebastian)