Many firms prohibit trades within a few minutes before and after high-impact events on the economic-calendar, such as nfp, cpi, and fomc. Violations can void profits or end the account, even when the trade was profitable.
The rule exists because news spikes produce slippage that would hurt a firm with real capital, and because they produce outsized gambling wins in simulation.
Example: a firm bans positions from 2 minutes before to 2 minutes after tier-1 news. A trader long ES through the 8:30 a.m. NFP release breaches the rule regardless of outcome.
Related: economic-calendar, nfp, cpi, fomc, slippage