SENSEX down by 500+ points- -What does this mean?

1. SENSEX is a trading symbol for a stock, commodity, fund or anything that trades on an exchange. If you want to trade shares or do research on a stock or a fund, you type in the trading symbol. 2. Points usually represent the units the stock/fund is traded in. Stock points generally represent dollars or cents per share. If a stock rises 50 points, and you hold 100 shares, the value of your stock rose $5,000. (Some refer to points as percentage points, but that is usually not what points mean). 3. I believe the value of the points is determined by the company or the exchange. Points rise or fall by buying and selling demand. You and I as traders determine the value of the stock. If the value of the stock gets too high in points, there is sometimes a decision to split the stock, which cuts the point value in half and doubles your number of shares (you don't gain or lose any money by a stock split). A reverse split is the exact opposite. A company does this when they want fewer numbers of shares outstanding. 4. Some are sector oriented and some are not. For example, a commodity futures contract of corn is in cents per bushel. Stocks are generally quoted in dollars/share. As far as how they determine the actual amount within sectors, I don't know. 5. I believe it is up to the exchanges and/or the company directors to determine the points. 6. The points systems, or quotes, are updated constantly throughout the trading day. How often depends on how active each market is. Many markets are very volatile and the price constantly fluctuates throughout the trading day. Back in the day, some markets only had a few trades per day. Usually, something in a newspaper like in your example, "SENSEX down by 500+ points" usually means it happened in one trading day.