NEW YORK, Aug 31 (Reuters) - Currency speculators turned negative on the U.S. dollar in the latest week for the first time in nearly a year, according to data from the Commodity Futures Trading Commission released on Friday. The value of the U.S. dollar's short position totaled $441.7 million from a net long position of position of $4.57 billion the previous week. It's the first net short position on the dollar since the week of Sept. 6, 2011. To be short a currency is to bet it will fall in value, while being long is a view its value will rise. 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. Euro net shorts further declined to 101,561 contracts this week, while net longs on the yen rose to 21,556 contracts. Euro sentiment has improved markedly the last few weeks on expectations of further peripheral bond buying by the European Central Bank in efforts to keep interest rates in debt-plagued countries lower. The euro zone's common currency ended the month of August on a positive note, notching gains of 2.3 percent after losses of 2.8 percent the previous month. The U.S. dollar index, on the other hand, closed this month down 1.7 percent following gains of 1.2 percent in July. Further weighing on the U.S. dollar was an increase in net longs on the Canadian dollar to 60,936 contracts and a decline in short bets on the Swiss franc to 11,461 contracts. JAPAN YEN (Contracts of 12,500,000 yen) -3,432,484,076.43 8/28/12 week 8/21/12 week Long 53,571 43,584 Short 32,015 32,413 Net 21,556 11,171 EURO (Contracts of 125,000 euros) 15,950,155,050.00 8/28/12 week 8/21/12 week Long 45,927 45,986 Short 147,488 169,918 Net -101,561 -123,932 POUND STERLING (Contracts of 62,500 pounds sterling) -194,536,800.00 8/28/12 week 8/21/12 week Long 42,407 45,984 Short 40,439 38,151 Net 1,968 7,833 SWISS FRANC (Contracts of 125,000 Swiss francs) 1,499,188,991.21 8/28/12 week 8/21/12 week Long 10,684 5,921 Short 22,145 21,583 Net -11,461 -15,662 CANADA DOLLAR (Contracts of 100,000 Canadian dollars) -6,166,363,084.40 8/28/12 week 8/21/12 week Long 86,639 76,008 Short 25,703 25,141 Net 60,936 50,867 AUSTRALIA DOLLAR (Contracts of 100,000 Aussie dollars) -8,097,627,840.00 8/28/12 week 8/21/12 week Long 124,137 127,500 Short 46,065 40,618 Net 78,072 86,882 MEXICO PESO (Contracts of 500,000 pesos) -3,588,668,082.52 8/28/12 week 8/21/12 week Long 104,239 107,140 Short 9,613 9,159 Net 94,626 97,981 NEW ZEALAND DOLLAR (Contracts of 100,000 NZ dollars) -1,144,438,470.00 8/28/12 week 8/21/12 week Long 18,215 19,835 Short 3,986 3,463 Net 14,229 16,372