Rally is the type of price movement when the prices of stocks, bonds, or other indexes increase in the short period of time. The occurrence of rallies is mostly fast. It means that there are substantial upside moves in the short period of time. Sometimes, rallies could occur during bear and bull markets. Thus, there are these terms called the bull market rally and the bear market rally. On the other hand, it still follows the price movement.
The opposite of a it is market crash or correction. Market crashes on the other hand happen when there is a rapid downward in the short-term prices. By definition, it refers to upward swings in the markets. The length of the rally could be different from one another depending on the markets. For a day trader for instance, the length could be the first 30 minutes of the trading day. This is in order to reach the new highs.
For a portfolio manager on the other hand, many retirement funds are looking at a larger picture. It could reflect the last calendar as a rally although the bear market happened last year. The cause of the rally is majorly from the increase in demand from a huge influx of investment capital into the market. Thus, it could trigger the beading up of prices. Then, the length of the rally also follows the delling pressure the buyers are facing.
There are also many buyers however there are only a few investors who like to share. But the large rally could likely happen. But, if the large buyers match the amount of sellers, it would even be short. Thus the price movement is low.