The US flagship shares index, the Dow Jones Industrial Average, has the power to influence investors around the world.
The stock market index has its origins more than 100 years ago.
Back then, the Customers Afternoon Letter, a forerunner of the Wall Street Journal, published the closing prices of 11 stock prices.
Original Dow Jones Industrial Average (1896)
American Cotton Oil
Distilling & Cattle Feeding
Tennesee Coal & Iron
US Leather preferred
The index is now made up of the share prices of 30 major US corporations, most of them traded on the New York Stock Exchange (NYSE).
Here, BBC News Online tracks some of the Dow's most important movements during the past century.
"Customers Afternoon Letter" publishes closing prices of 11 stocks - nine railroads, Western Union and Pacific Mail.
Closing average price not available.
16 February 1885
The average closed at 62.76, the first time it is published on a regular basis, and includes 14 stocks - 12 railroads and two industrials.
26 May 1896
Charles Dow introduces the first index composed entirely of industrial shares, covering 12 companies. The Dow Jones Industrial Average is born.
12 January 1906
Sign of success
Index closes at 100.25, the first close above 100. President Theodore Roosevelt is in office. The New York Stock Exchange trades 260m shares for the year.
12 March 1956
First close over 500 at 500.24. Dwight Eisenhower is in the White House. Trading on the New York Stock Exchange totals 766m shares for the year.
14 November 1972
The Dow tops 1,000 to end at 1,003.16. President
Richard Nixon is in office. The index briefly reached
1,000 in early 1966 but retreated and closed below that milestone. The NYSE trades nearly 3bn shares for all of 1972.
8 January 1987
First close above 2,000 at 2,002.25. President Ronald Reagan is in office.
19 October 1987
The index falls 508 points to 1,738.74, the biggest one-day drop in its history, wiping 22.6% off its value in one day.
13 July 1990
Dow Jones stocks (March 2001)
Johnson & Johnson
Procter & Gamble
The Dow hits 3,000 for the first time but falls back to close at 2,980.20.
17 April 1991
Dow ends above 3,000 for the first time at 3,004.46. George Bush is president, facing a severe budget deficit. 40bn shares are traded on the NYSE for the year.
23 February 1995
First close above 4,000 at 4,003.33 amid euphoria that interest rates were peaking. Bill Clinton is in the White House.
21 November 1995
Ends above 5,000 for the first time at 5,023.54, passing two millennium markers in the same year.
14 October 1996
The Dow breaks through the 6,000 points level for the first time and closes at 6,010.00, double where it stood just five-and-a-half years earlier. NYSE volume routinely exceeds 2bn shares per week.
13 February 1997
Just four months later, the Dow Jones has added another 1,000 points to close above 7,000.
16 July 1997
Watching the stocks go up
The Dow Jones index closes above 8,000. In less than two-and-a-half years the Dow Jones has managed to double in size.
27 October 1997
Chaos on Asia's financial markets leads to a global selloff. The Dow Jones index falls 554 points - its biggest single-day point drop. However, as the index has dramatically grown in size, this amounts to "only" 7.2% of the Dow's overall value. For the first time curbs - that were instituted after the 1987 crash - halt trading for 30 minutes after the Dow falls 350 points.
After the Dow falls more than 550 points, trading is halted again for the final 30 minutes of trading.
28 October 1997
The next day, Wall Street leads a global stock rebound. The Dow finishes up 337 points, or 4.7%, at 7,498, its fourth-biggest single-day points gain. NYSE daily volume tops 1bn shares for the first time, ending the day at 1.2bn shares traded.
3 April 1998
The Dow rises above 9,000 points early in the session as a surprisingly weak report on U.S. employment sends interest rates lower.
17 July 1998
New heights are scaled as the Dow closes at 9,337 points.
4 August 1998
The Dow closes 299.43 points down at 8487.31 - then the index's third biggest one-day points loss.
31 August 1998
Another bad day for Wall Street. The 'bears' are rampant as the Dow Jones drops to 7,539 - down 512 points or more than 6%. The Dow has now lost 19.2% since its high in July.
17 March 1999
For the first time the index sails past the 10,000 points mark - but profit taking in the afternoon drives down share prices and the Dow closes at 9,931 points. The feat is repeated during the following two days, but the index always closes in the four-digit range.
29 March 1999
"Dow 10,000" - after a surge of 170 points the Dow Jones closes at 10,006.78 - for the first time above the 10,000 level.
03 May 1999
"Dow 11,000" - up 225 points to close at 11,014. It takes the Dow just over a month to reach this landmark, the fastest 1,000 points jump. Records tumbled during April, as the Dow steadily edged towards this new all-time high.
14 January 2000
The Dow peaks at 11,722.98 points.
7 March 2000
After a series of vicious sell-offs, the Dow plunges to the year's low of 9,796.03. In the following months, the index trades in a range of about 10,200 to 11,300 points.
16 March 2000
In days of high volatility, the Dow Jones posts its biggest single day points gain in history, gaining 499.19 points or just under 5% to close at 10630.60
14 April 2000
Biggest points loss in history, with the Dow shedding 617.78 points or 5.66% to close at 10305.77
14 March 2001
The Dow plunges below the 10,000 points level again, prompted by an economic slowdown in the United States, and hefty losses on global technology markets.
11 September 2001
The terrorist attacks on New York halt trading for an unprecedented four days, with the index stuck at 9,605.
21 September 2001
Fears over the attacks and the impact on the world economy send the Dow down to 8,236 - the lowest point reached in the aftermath of the 11 September.
5 December 2001
A steady rebound from the September lows and new hopes of economic recovery pull the index back over 10,000 for the first time since the attacks. But a wave of corporate scandals is already beginning to break.
23 July 2002
The scandals - including infamous energy giant Enron and telecoms firm WorldCom - shakes the confidence of investors to the core. The Dow falls
back below its post-11 September lows to 7,702 points.