METALS-LME copper climbs after 4 sessions of losses; Jackson Hole eyed

* LME copper up, snaps 4 sessions of losses
* Jackson Hole eyed for possible QEIII after ex-BOE banker
comment
* Chinese copper spot-to-prompt-futures premium narrows
* ShFE copper backwardation boosts exchange stock build
* Coming Up: U.S. Fed chief speaks at Jackson Hole; 1400 GMT

By Carrie Ho
SHANGHAI, Aug 31 (Reuters) - London copper was on track to
snap four sessions of losses on Friday, inching up as investors
covered short positions ahead of the Jackson Hole meeting of
central bankers, where they hope the United States Federal
Reserve will do more to boost the economy.
Hopes of the U.S. and other major economies launching more
stimulus were stirred after outgoing Bank of England member Adam
Posen said on Thursday the world's top central banks had room to
ease monetary policy further.
"Investors don't know if the Fed will introduce a new round
of policy easing tonight, and they know that a QEIII will not be
as effective as the previous ones," said a Shanghai-based copper
buyer.
"But even with these doubts, everyone still prefers to exit
their positions before Bernanke's Jackson Hole speech, since you
never know how the markets will react in these uncertain times.
This cautious sentiment will keep copper prices moving within a
tight range today," he added.
Three-month copper on the London Metal Exchange
ticked up just $3 to $7,570.50 per tonne by 0716 GMT, after four
straight sessions of losses and on course to log a 0.2 percent
monthly gain.
The most active December copper contract on the Shanghai
Futures Exchange fell 0.5 percent to 55,420 yuan
($8,700) per tonne, catching up with previous losses in London.
It is on track to post a 1.2 percent rise on the month.
In the Chinese physical markets, spot copper prices are
trading at a premium of around 50 yuan to Shanghai September
copper futures on Friday, traders said.
"That physical premium shrank from 350-400 yuan two weeks
ago, after Jinchuan bought around 20,000 tonnes of spot copper,
which stirred speculative interest," said a Shanghai-based
physical trader.
"Trading has livened up in the second half of August
compared to the month before, but volumes are much lower than
previous years as downstream copper demand is still weak."
The recent pickup in spot copper sales is also reflected in
the backwardation of Shanghai copper futures, which has led to
traders drawing down bonded copper stocks and putting them on
warrants on the Shanghai Futures Exchange.
"Shanghai prices outperformed and that drew in a bit of
metal, so we've seen a bit of a build in stocks through the
customs clearance in Shanghai," said a Hong Kong-based trader.
"Sellers have become more interested in selling copper after
prices rose recently. But people are more interested in buying
and selling copper for near-dated deliveries as future
uncertainties still weigh on forward futures contracts," said
the physical copper trader.

TIN EXTENDS LOSSES
In other metals, LME tin fell 0.5 percent to $19,502
a tonne, extending losses to a fourth session and is on track to
post 6.7 percent fall on the week -- biggest weekly drop in more
than six months.
"Investors started taking profit in tin futures this week
after news of PT Timah's restart. Caution ahead of Bernanke's
speech tonight also added to the selling," said a
Singapore-based trader.
Indonesian tin producer PT Timah has re-started
spot sales after a three-week stoppage, a company executive said
on Wednesday, as benchmark prices for the base metal rose.

Prices had shot up 13 percent last week, rising to as high
as $20,901, on news that more than 90 percent of Indonesian tin
producers had stopped production.

Base metals prices at 0716 GMT
Metal Last Change Pct Move YTD pct chg
LME Cu 7570.50 3.00 +0.04 -0.39
SHFE CU FUT DEC2 55420 -260 -0.47 -0.38
LME Alum 1869.75 -7.25 -0.39 -7.44
SHFE AL FUT DEC2 15330 -60 -0.39 -3.22
HG COPPER SEP2 344.10 0.05 +0.01 0.15
LME Zinc 1838.00 4.00 +0.22 -0.38
SHFE ZN FUT DEC2 14685 -105 -0.71 -0.74
LME Nickel 16060.00 85.00 +0.53 -14.16
LME Lead 1953.00 9.00 +0.46 -4.03
SHFE PB FUT 15130 -95 -0.62 -1.05
LME Tin 19502.00 -98.00 -0.50 1.57
LME/Shanghai arb 813

Shanghai and COMEX contracts show most active months
^ LME 3-m copper in yuan, including 17 pct VAT, minus SHFE
third month