Wall Street influences Main Street and even the rest of the world. “When Wall Street sneezes,” the saying goes, “the rest of the world catches pneumonia.” The phrase has several variations, with “America” or “United States” replacing “Wall Street” and with “cold” replacing “pneumonia.” The most frequent variation involves replacing “the world” with “Europe” or “Germany” or “Japan.”
   
The origin of the phrase is unknown, but it appeared frequently in newspapers in the 1950s and 1960s. (The 1926 citation below needs to be verified; Google Books is sometimes unreliable.) 
 
     
20 December 1906, Wall Street Daily News, pg. 1:
Your English, French, or German investor does not shake in his shoes every time Wall Street sneezes. 
 
Google Books
Readings in Money, Credit and Banking Principles
Compiled by Ivan Wright
New York, NY: Harper & Brothers
1926
Pg. 343:
At one time it was a common saying, “When Wall Street sneezes every country banker has a chill.”
       
9 November 1952, New York (NY) Times, “Europe Wonders How Long U.S. Vote Will Hamstring It” by Harold Callender, pg. 13:
Today when the United States sneezes it means the Western world has a cold. 
 
31 May 1954, Winnipeg Free Press, “Slump Panic Needless, Briton Says,” pg. 1, col. 3:
“Wise economists have warned us that if America sneezes, we would catch pneumonia.”
(Peter Thorneycroft, president of United Kingdom Board of Trade—ed.)
 
13 December 1955, Modesto (CA) , “British Consul States US Must Develop World Trade,” pg. 21, col. 3:
“Economically speaking, every time America sneezes, the rest of the world has pneumonia,” he said.
   
Google Books
Introduction to Money
By Honor Minturn Croome
New York, NY: Barnes & Noble
1956
Pg. 199:
When America sneezes, it has been said, the rest of us get pneumonia; and it is argued accordingly that the benefits of unrestricted access to American ...
   
2 March 1956, El Paso (TX) Herald-Post, pg. 20, col. 7:
They envy our prosperity—even the Reds don’t deprecate it. They say: “If America sneezes, Europe gets pneumonia.”
 
Google Books
America’s Next Twenty Years
By Peter Ferdinand Drucker
New York, NY: Harper
1957
Pg. 73:
This was well expressed in the slogan of a few years back: “When the United States sneezes, Europe catches pneumonia.”
 
14 October 1957, New York (NY) , ‘Foreign Affairs; Can Asian Flu Come From America?” by C. L. Sulzberger, pg. 26:
When Wall Street sneezes, Tokyo catches influenza.
   
1 December 1957, New York (NY) Times, ‘Trend of U.S. Economy Is Scrutinized Abroad” by Edwin L. Dale, Jr., pg. 235:
WASHINGTON, Nov. 30—At the beginning of the present decade it was said of the world economy that “when America sneezes, Europe catches pneumonia.”
   
Google Books
The New Japan
By Elizabeth Velen, Victor A. Velen
New York, NY: H.W. Wilson Co.
1958
Pg. 112:
When Wall Street sneezes, Tokyo catches influenza.
 
30 December 1960, Corpus Christi (TX) Times, pg. 14, col. 3:
NEW YORK—When the American economy sneezes, New England often as not catches cold.
   
3 June 1962, New York (NY)

, “European View: Economists Feel Payments Deficit is Washington’s Most Serious Problem” by Edwin L. Dale, pg. 173:
In any case, the events of this week on Wall Street have revived the old phrase about “when America sneezes, Europe catches pneumonia.”
 
8 June 1962, Lowell (MA )Sun, “Germans Believe Prosperity High” by Edgar Ansel Mowrer, pg. 6, col. 4:
BONN—When stock prices fell sharply in New York the last Monday in May, prices of securities tumbled all over Europe. Which recalls a current saying: “When Wall Street sneexes, every investor in Europe blows his nose.” And apparently nowhere more than in Germany.
 
29 July 1962, Bridgeport (CT) Post, “Japanese Differ on Economic Ties With U.S.,” pg. 9, col. 5:
TOKYO—(UPI) When Wall Street sneezes, it is sometimes said in Japan, the ginza catches cold.
 
3 February 1963, The Progress-Index (Petersburg, VA),, pg. 6, col. 2:
Observers note that an unseasonal slowdown in auto sales usually precedes any general business slowdown, a phenomenon which has led to the maxim that when the economy sneezes, Detroit catches pneumonia.
 
1 September 1963, Syracuse (NY) Post-Standard, “Wall Street Sneezes and the World Gets Pneumonia” by Ed Morse, pg. 8, col. 1: 
NEW YORK (AP)—Why all the hullabaloo about the stock market?
 
Why is it big news that the government wants it regulated more strictly? How does the market affect you and me?
 
“When Wall Street sneezes,” the saying goes, “the rest of the world catches pneumonia.” Why?
 
5 November 1987, Washington (DC) Post, “Crash Course in Finance” by Art Buchwald, pg. B1:
Q. There is a well known saying that when Wall Street sneezes, the rest of the world gets pneumonia. Is there any truth to this?
 
NPR
Economy
When America Sneezes, Cliches Spread
Listen Now [1 min 54 sec]
Morning Edition, January 24, 2008 · As stock markets around the world respond to turbulence in the U.S., variations on a dusty old theme are heard over and over in the media and elsewhere: “When America sneezes, the world catches cold.”