Benchmark copper on the London Metal Exchange has broken the key level of $6,400 a tonne, which marks the upper boundary of a range that has held for the past six months, he added. "If this confirmed today on the weekly chart with a close above $6,400, it would mark the start of new bull cycle for copper."
LME copper gained 1.6 percent in closing open outcry trading to $6,478 a tonne, its highest since July 4. The metal, widely used in construction and manufacturing, posted a 4.6 percent gain this week, its biggest weekly jump since the week ended Sept. 21 last year.
On-warrant LME copper inventories, those not earmarked for delivery, slumped by nearly half to 39,800 tonnes in one day, the lowest since August 2005, LME data showed on Friday. LME aluminium gained 0.4 percent to finish at a two-week high of $1,913 a tonne.
Recent gains have been driven by speculators covering short positions, Alastair Munro at broker Marex Spectron said in a note. The LME net speculative short position accounted for 17.6 percent of open interest, according the Marex estimates. Falling LME zinc inventories, hovering at the lowest levels in more than a decade, may spur prices higher, metals strategist Michael Widmer at Bank of American Merrill Lynch said in a note.
"With inventories so low, it is easier for market participants to take a dominant position, which in turn could lead to prices squeezing violently higher." LME nickel climbed 1.1 percent to end at a two-week high of $12,990 a tonne after on-warrant LME inventories fell to 128,580 tonnes, the lowest since February 2013. Zinc gained 1.5 percent to close at $2,724 a tonne, lead added 0.4 percent to $2,075 and tin rose 0.3 percent to $21,495.