The US Stock Market. At least within the context of the last decade and probably the next decade. It is all about the value of the US dollar.
The value of the dollar goes down and the Stock Market, (which is a market of stocks), Oil, Gold and all other assets priced in dollars goes up. If the dollar, which was worth a dollar yesterday is only worth 98 cents today, people want more dollars for the same basket of goods.
When the value of the dollar goes up convincingly, all of this stuff goes down. That's it. That's all you need to know.
Watch it and you will see that 90+% of the time even to the day that the US dollar rallies and goes up in value, the market heads down. More specifically, it is re-priced down. I say 90+% of the time because the 'market' is not a Swiss Watch. If it were and were always logical on each and every day it would be too easy to profit from. People would program their computers to trade and everyone would get rich. An impossibility.
Anyway, an easy way to think of it is: When the value of the dollar goes down, OPEC wants more dollars for their one and only world distributed product - oil. Gold is also easily correlated to movements in the value of the dollar. Dollar up, gold down. Dollar down, Gold up.
By the way, don't you love it when they show a picture of stock trading floor traders looking worried or holding their heads in their hands becuase the DOW went down 150 points? These people make money both ways, coming and going. Please...
The market has been rallying and has lately been held up because of all of The Fed's actions which served to devalue the dollar. Specifically, the printing of trillions of dollars to buy/trade worthless mortgage paper from the banks and returning real money in the form of US Treasuries - that actually have some value. They called that Quantitative Easing. They should have called it Raping America with telephone poles.
The market itself is a bit more fuzzy because it is valued not only by the dollar but by the actions of specific companies. eg. IBM doubles its sales and profit. "The market" or at least IBM and Technology stocks are going up regardless. IBM is worth more dollars even if the dollars are worth more.
I'm not waffling. I'm saying that on 2 out of 100 days, the dollar and Gold or Oil or the Market or all of these have been up together. That is an anomaly. It won't stay that way for long. More than a day or two in fact.
So, when the person from CNN or ABC, or even the Wall Street Journal prints a story with a headline that reads "Stocks Rally on Big Black Friday Sales!" or "Stocks are Sold on Tensions in Middle East!", or any of that nonsense, just smile to yourself, look at what the dollar did and what the market did.
Why do "news people" - some of the dumbest people on Earth anyway - feel it necessary to try to explain the movements of the stock market? Why don't they just say "Market Up (or Down) Today. No One Knows Why"