Figure 2

Market activity in 78 stocks in the three minutes after an ALERT or a HEADLINE are displayed. The ticker symbol corresponding to each stock number is provided in Table 1. (a), (b), and (c) show the normalized number of transactions, \(\langle N(0 \le\Delta t<3) \rangle \), the normalized volume, \(\langle V(0 \le\Delta t<3) \rangle\), and the normalized volatility, \(\langle \mathit{Vol}(0 \le\Delta t<3) \rangle\). The error bars shown are for ALERTs and are calculated using randomized data (i.e., the timing of the arrival of news is randomized). The error bars for HEADLINEs are not shown to make the figures easier to read.