By Gertrude Chavez-Dreyfuss

NEW YORK, Jan 21 (Reuters) - Speculators' net long positioning on the U.S. dollar dropped in the latest week to its lowest level since mid-September 2021, according to calculations by Reuters and U.S. Commodity Futures Trading Commission data released on Friday.

The value of the net long dollar position fell to $12.59 billion for the week ended Jan. 18, from $19.34 billion the previous week.

Scotiabank, in its report after the release of the CFTC data, said this was one of the largest weekly declines in long dollar positioning since mid-2020.

U.S. dollar positioning was derived from net contracts of International Monetary Market speculators in the Japanese yen, euro, British pound, Swiss franc, as well as Canadian and Australian dollars.

In a wider measure of dollar positioning 0#NETUSDFX= , which includes net contracts on the New Zealand dollar, Mexican peso, Brazilian real and Russian rouble, the greenback posted a net long position of $13.028 billion this week, from $19.906 billion in the prior week.

"Investors were gripped with a sudden, and perhaps short-lived, given subsequent developments, burst of enthusiasm for the euro last week as spot euro showed some fleeting strength and tested levels near $1.15," said Shaun Osborne, Scotia's chief FX strategist, in the report.

Data showed euro net longs rose to 24,584 contracts this week, from 6,005 the previous week. In the case of the dollar, higher Treasury yields have not boosted the greenback as much, with many investors taking the view that most of the recent hawkishness from the Federal Reserve has already been priced in.

So far this year, the dollar index has been flat even though U.S. 10-year Treasury yields have risen 20 basis points. The benchmark yield was last at 1.7705% US10YT=RR .

In cryptocurrencies, bitcoin futures' net short positions dropped to 549 contracts this week, from 377 the previous week. The latter was the smallest net short since late September.

Bitcoin and crypto sentiment overall has been fragile for most of the month, as investors moved away from riskier assets ahead of Federal Reserve meeting next week, which is expected to flag an interest rate increase in March.

The world's largest digital currency has also been affected by news that Russia has proposed a ban on the use and mining of cryptocurrencies.

Bitcoin was last down 10% at $36,660 BTC=BTSP , after earlier dropping to a six-month low. Since the beginning of the year, bitcoin has lost 20% of its value versus the dollar.

Japanese Yen (Contracts of 12,500,000 yen) $8.821 billion

18 Jan 2022

Prior week

week

Long

8,002

22,364 Short

88,881

109,889 Net

-80,879

-87,525 EURO (Contracts of 125,000 euros) $-3.48 billion

18 Jan 2022

Prior week

week

Long

211,901

204,361 Short

187,317

198,356 Net

24,584

6,005 POUND STERLING (Contracts of 62,500 pounds sterling) $0.021 billion

18 Jan 2022

Prior week

week

Long

39,760

30,506 Short

40,007

59,672 Net

-247

-29,166 SWISS FRANC (Contracts of 125,000 Swiss francs) $1.473 billion

18 Jan 2022

Prior week

week

Long

925

4,571 Short

11,735

12,231 Net

-10,810

-7,660 CANADIAN DOLLAR (Contracts of 100,000 Canadian dollars) $-0.599 billion

18 Jan 2022

Prior week

week

Long

49,792

44,284 Short

42,300

51,660 Net

7,492

-7,376 AUSTRALIAN DOLLAR (Contracts of 100,000 Aussie dollars) $6.353 billion

18 Jan 2022

Prior week

week

Long

9,051

12,383 Short

97,505

103,869 Net

-88,454

-91,486 MEXICAN PESO (Contracts of 500,000 pesos) $-0.121 billion

18 Jan 2022

Prior week

week

Long

75,461

53,194 Short

70,541

57,645 Net

4,920

-4,451 NEW ZEALAND DOLLAR (Contracts of 100,000 New Zealand dollars) $0.564 billion

18 Jan 2022

Prior week

week

Long

11,612

10,960 Short

19,943

19,564 Net

-8,331

-8,604
Reporting by Gertrude Chavez-Dreyfuss Editing by Chris Reese and David Gregorio