“Copper is the only commodity with a Ph.D. in economics” (Wall Street adage)

“Copper is the only commodity/metal with a Ph.D. in economics” is a Wall Street adage, resulting in the nickname “Dr. Copper.” Copper is an important industrial metal. If copper’s price is rising, industry is doing well; if copper is falling, then industry is doing poorly.
   
“Dr. Copper, the metal with a Phd. in economics” has been cited in print since at least 1998.
 
 
The Keystone Speculator
Wall Street Witty Quotes
(...)
“Copper is the metal with a PhD in economics.”  Wall Street adage
     
13 December 1998, New York (NY) Post, “Copper, the metal that gets no respect, needs a break” by John Dizard, pg. 78: 
The red metal is sometimes called “Dr. Copper, the metal with a Phd. in economics,” because its price has historically tracked economic prospects closely.
 
InvestorVillage
Posted 3/2/2004 11:20:25 PM by poolit5
(...)   
Copper is often referred to as “Dr. Copper… the metal with a Ph.D. in economics” because it is said to predict trends. When copper goes down, the economy follows. When it goes up… the economy soon gets “overheated,” with rising consumer prices.
   
Stock Trading Letter
Sunday, October 17, 2004
The metal with a PhD in economics
Copper has been called the metal with a PhD in economics because it is so sensitive to economic trends
 
Miningmx
Copper linked with economic rebound
Garth Theunissen | Fri, 20 Apr 2007 15:00
[miningmx.com]—ECONOMISTS like to joke that copper is the only metal with a PhD in economics, thanks to its uncanny ability to forecast global economic growth.
 
World of Wallstreet
January 16, 2009
Weekly Copper And Zinc Inventory Report
(...)
Copper is often referred to as Doctor Copper because, ostensibly, it has a Phd in economics. That is, it is a good indicator of the global economy. So, its worth keeping an eye on even if you don’t intend to actively invest in it.
   
OilPrice.com
Is Copper the New Red Gold?
By Mad Hedge Fund Trader | Thu, 02 September 2010 01:07
(...)
Long known as “Dr. Copper”, because it is the only commodity with a PhD in economics, the red metal has long been an excellent forecaster of economic activity around the world.
     
Wall Street Journal—MarketBeat
October 25, 2010, 12:32 PM
The Coming Death of Dr. Copper
By Matt Phillips
Dr. Copper is living on borrowed time.
 
As avid MarketBeaters know, the industrial metal copper occupies an outsized position in the mind of investors. Such is the reputation of copper that, among Wall Streeters, the metal is sometimes called “Dr. Copper” — the metal with a PhD in economics — because its prices are believed to signal turning points in the global economy.
 
Google Books
The Wall Street Journal guide to the 50 economic indicators that really matter:
From Big Macs to “zombie banks,” the indicators smart investors watch to beat the market
By Simon Constable and Robert E. Wright
New York, NY: Harper Business
2011
Pg. ?:
IT’S AN INVESTING MAXIM that copper is the metal with a PhD in economics. Why so? Well, it isn’t really the metal itself, but rather its price that is the smart part of the equation.
 
Broadly speaking, if the price is relatively high and rising, then the industrial economy is doing well. If it’s low and falling, then the manufacturing sector is hurting. Why? “Because,” according to Frank Holmes, chief investment officer of San Antonio-based U.S. Global Investors, “copper has unique physical properties that make it the backbone of the industrial economy.”