When a trading-halt lifts — news pending, a volatility pause, or a circuit-breaker — the venue does not simply reopen the continuous book. It runs a cross with an indication period so both sides can see where the market wants to trade.
This is the moment retail stop orders do the most damage. A stop-order resting under a halted stock becomes a market order at the reopen and pays whatever the cross sets.
Example: a biotech halts at 18.00 on pending news; the trial failed. Indications during the pause walk from 12 down to 7.40. The halt auction prints 7.40. A stop-loss at 17.00 does not sell at 17.00 — it sells at 7.40, a 55% gap below the trigger. This is gap-risk, not broker error.
Related: trading-halt, gap-risk, stop-order-slippage, limit-up-limit-down