Copper futures have risen nearly 18 percent this year, a run that Phil Streible, senior market strategist at RJO Futures, deemed "incredible."
But after touching its highest level of the year last week, the metal is surely set to cool off, he said Friday in an interview.
"If you're currently long copper, you might want to take those positions off and look to reallocate in other safe haven metals, like gold, silver, platinum, palladium. But the copper market, I think, has definitely peaked," Streible said on CNBC's "Trading Nation. "
In fact, copper just logged two straight weeks of declines; prior to that, the metal often seen as a rough gauge of global economic growth notched eight straight weeks of gains.
Investors ought to keep an eye on Chinese economic growth, Streible said. China is one of the world's largest consumers of the industrial metal, and its prices can be vulnerable to economic reports out of the country.
Two measures of growth missed this week; Chinese factory output fell below economists' expectations, as did fixed-asset investments.
"Chinese economic data showed the lowest reading for industrial production, which dampens the [country's] demand outlook … also while most likely storm related, U.S. industrial production unexpectedly declined today as well," Streible wrote in an email to CNBC on Friday, referring to Federal Reserve data that reflected the first monthly decline since January.
Traders' positioning in copper futures may also be signaling a bigger reversal ahead, if recent data published by the Commodity Futures Trading Commission is any indication.
"Short dollar, long metals, long gold, and long rates have been persistent trends in 2017, but all suffered a violent reversal at the same time around September 8th. CFTC data reveals that speculator positioning in copper, gold, Euro, and Canadian dollar FX futures was stretched," Pravit Chintawongvanich of Macro Risk Advisors wrote in a note to clients on Thursday.
Copper traded slightly lower on Friday.