The symbol ^ in Dow Jones Industrial Average (^DJI) represents that the following letters and characters constitute a ticker symbol. In this case, it indicates that "DJI" is the ticker symbol for the Dow Jones Industrial Average, a stock market index that measures the performance of 30 large, publicly owned companies in the United States.
Similarly, you may see it before SPX, which refers to the S&P 500 INDEX (^SPX).
The use of ^ before the ticker symbol is a convention to differentiate index symbols from individual stock symbols. It helps investors and traders quickly identify that they are looking at an index rather than a specific company's stock. The Dow Jones Industrial Average is one of the most widely followed and recognized stock market indices in the world, providing insight into the overall health and performance of the U.S. stock market.
The symbol ^ is called a caret. In various contexts, a caret can have different meanings or functions. In the context of financial markets and stock ticker symbols, as in ^DJI for the Dow Jones Industrial Average, it serves to indicate that what follows is a ticker symbol.
Carets are also commonly used in mathematics and computer programming for various purposes, such as denoting exponentiation or indicating where text should be inserted or deleted.