By Dion Rabouin
Sept 15 (Reuters) - Speculators raised their short bets against the U.S. dollar for the fourth consecutive week, with the value of contracts against the greenback increasing to $11.57 billion in latest week, the largest since January 2013, according to data from the Commodity futures Trading Commission calculated by Reuters.
The value of the dollar's net short position, derived from net positions of International Monetary Market speculators in the yen, euro, British pound, Swiss franc and Canadian and Australian dollars for the week ending Sept. 12.
Net long contracts on the Mexican peso rose to the highest level since May 2013.
The dollar appreciated early in the week, bouncing back from last week's trading that pushed the euro to its highest level against the greenback in 2-1/2 years and sterling at its highest versus the dollar in more than a year.
Market participants are expecting the European Central Bank to announce an unwinding to its massive quantitative easing program in the near future. Policymakers at the Bank of England this week also suggested they may raise the country's overnight interest rates from current historically low levels.
Investors will next look to Wednesday's Federal Open Market Committee meeting, in which the Fed is expected to start reducing its $4.5 trillion balance sheet. There is, however, zero expectation for an interest rate hike.
"The Fed's tone and stance during next week's FOMC statement and press conference will play a major role in setting expectations for interest rates, the Fed's balance sheet reduction plans, and the U.S. dollar going forward," said James Chen, head of research at Forex.com in Bedminster, New Jersey.
The Reuters calculation for the aggregate U.S. dollar position is derived from net positions of International Monetary speculators in the yen, euro, British pound, Swiss franc and Canadian and Australian dollars.
Japanese Yen (Contracts of 12,500,000 yen) $6.502 billion
Sept. 12, 2017
Prior week
week
Long
40,642
47,285 Short
97,939
120,230 Net
-57,297
-72,945 EURO (Contracts of 125,000 euros) $-12.871 billion
Sept. 12, 2017
Prior week
week
Long
191,102
194,976 Short
105,044
98,667 Net
86,058
96,309 POUND STERLING (Contracts of 62,500 pounds sterling) $3.826 billion
Sept. 12, 2017
Prior week
week
Long
68,938
54,454 Short
115,023
107,381 Net
-46,085
-52,927 SWISS FRANC (Contracts of 125,000 Swiss francs) $0.171 billion
Sept. 12, 2017
Prior week
week
Long
13,556
11,892 Short
14,870
14,063 Net
-1,314
-2,171 CANADIAN DOLLAR (Contracts of 100,000 Canadian dollars) $-4.145 billion
Sept. 12, 2017
Prior week
week
Long
91,645
94,732 Short
41,146
41,088 Net
50,499
53,644 AUSTRALIAN DOLLAR (Contracts of 100,000 Aussie dollars) $-5.054 billion
Sept. 12, 2017
Prior week
week
Long
101,713
103,353 Short
38,680
38,449 Net
63,033
64,904 MEXICAN PESO (Contracts of 500,000 pesos) $-3.3 billion
Sept. 12, 2017
Prior week
week
Long
143,188
141,051 Short
26,190
27,439 Net
116,998
113,612 NEW ZEALAND DOLLAR (Contracts of 100,000 New Zealand dollars) $-0.9 billion
Sept. 12, 2017
Prior week
week
Long
25,150
26,773 Short
12,800
12,050 Net
12,350
14,723