Whenever people buy or sell stock, they must report the transaction to the exchange. The exchange then forwards that report. The report of a single transaction is called a print. This is short for “print the tape.” The print includes the time, the stock symbol, the average price, and the total number of shares.
A print is the smallest piece of data related to buying stock. Our alerts server looks at each print for all stocks that we track. Some alerts can be based on a single print; these are the fastest alerts, but they also have the most noise. The alerts server also accumulates data about all prints for a stock and performs statistical analysis on that data. This allows us to filter out the noise.