Trading halts are typically imposed by either the stock exchanges or a regulator. They can occur for a number of reasons, such as waiting for substantial news to be released or during periods of high volatility.
Trading halts can interrupt your orders to buy or sell particular securities. In most cases, trading resumes within an hour. However, certain instruments may experience multiple halts within a single session or extended halts lasting more than one business day.
If a stock is halted, we'll try to add a notice to the instrument's page. You can also refer to the relevant exchange's website for information on historic and ongoing trading halts.