We investigate the relation between trading activity - measured by the number of trades [iopmath latex="$N_{Delta t}$"] Nt [/iopmath] - and the price change [iopmath latex="$G_{Delta t}$"] Gt [/iopmath] for a given stock over a time interval [iopmath latex="$[t,~t+Delta t]$"] [t, t + t]...

H Eugene Stanley and Vasiliki Plerou comment on the paper by Blake LeBaron, on page 621 of this issue, by examining the degree to which the twin concepts of scaling and universality apply to economic systems as compared with other physical systems comprising a large number of interconnected and...

Financial markets exhibit a complex hierarchy among different processes, e.g. a trading time marks the initiation of a trade, and a trade triggers a price change. High-frequency trading data arrive at random times. By combining stochastic and agent-based approaches, we develop a model for...