UPDATE 1-Speculators pare back U.S. dollar longs to 4-month low -CFTC, Reuters

By Gertrude Chavez-Dreyfuss

NEW YORK, Feb 17 (Reuters) - Speculators reduced bullish bets on the U.S. dollar to their lowest in four months, cutting net longs for a sixth straight week, according to Commodity Futures Trading Commission data released on Friday and calculations by Reuters.

The value of the dollar's net long position totaled $14.99 billion in the week ended Feb. 14, down from $17.07 billion the previous week. The latest dollar positioning was the lowest since the week ended Oct. 11.

The dollar has underperformed so far this year, falling 1.2 percent against a basket of currencies, after gains of 3.6 percent in 2016.

The dollar has been hurt by a combination of comments from the Trump administration about preference for a weaker dollar as well as mixed U.S. economic data suggesting growth in the world's largest economy may not be as strong as many initially thought.

The greenback's soft trend so far in 2017, however, is not expected to last long with a Federal Reserve in the midst of an interest rate hiking cycle. Fed Chair Janet Yellen earlier this week affirmed the U.S. central bank's commitment to raising interest rates multiple times this year, noting that "every FOMC (Federal Open Market Committee) meeting is a live meeting."

"It is only a matter of time before the dollar resumes its rise," said Kathy Lien, managing director of FX strategy at BK Asset Management in New York.

"The (dollar) bulls could be hanging back until President Trump announces his 'phenomenal' tax plan," she added.

CFTC data also showed net shorts of 51,284 Japanese yen contracts, the lowest in more than two months.

The yen has gained 3.5 percent so far this year as the U.S. dollar struggled. The Japanese currency's movements have been mostly tied to the greenback's outlook.

"The inability of U.S. bond yields to hold onto recent gains highlights the fading confidence surrounding the administration's ability to enact swift and meaningful fiscal legislation," said Omer Esiner, chief market analyst at Commonwealth Foreign Exchange in Washington.

The Reuters calculation for the aggregate U.S. dollar position is derived from net positions of International Monetary Market speculators in the yen, euro, British pound, Swiss franc and Canadian and Australian dollars.

Japanese Yen (Contracts of 12,500,000 yen) $5.611 billion

14 Feb 2017 Prior week

week Long 27,701 25,874 Short 78,985 80,934 Net -51,284 -55,060 EURO (Contracts of 125,000 euros) $6.183 billion

14 Feb 2017 Prior week

week Long 125,333 126,708 Short 172,097 171,659 Net -46,764 -44,951 POUND STERLING (Contracts of 62,500 pounds sterling) $5.106 billion

14 Feb 2017 Prior week

week Long 39,039 38,135 Short 104,567 102,674 Net -65,528 -64,539 SWISS FRANC (Contracts of 125,000 Swiss francs) $1.428 billion

14 Feb 2017 Prior week

week Long 6,608 7,059 Short 18,092 21,680 Net -11,484 -14,621 CANADIAN DOLLAR (Contracts of 100,000 Canadian dollars) $-1.479 billion

14 Feb 2017 Prior week

week Long 53,152 46,127 Short 33,812 37,577 Net 19,340 8,550 AUSTRALIAN DOLLAR (Contracts of 100,000 Aussie dollars) $-1.855 billion

14 Feb 2017 Prior week

week Long 79,313 66,545 Short 55,095 49,797 Net 24,218 16,748 MEXICAN PESO (Contracts of 500,000 pesos) $1.486 billion

14 Feb 2017 Prior week

week Long 30,271 31,229 Short 90,484 89,717 Net -60,213 -58,488 NEW ZEALAND DOLLAR (Contracts of 100,000 New Zealand dollars) $-0.206 billion

14 Feb 2017 Prior week

week Long 36,565 34,860 Short 33,689 33,015 Net 2,876 1,845 (Reporting by Gertrude Chavez-Dreyfuss; Editing by Richard Chang and Meredith Mazzilli)