GTC extended hours refer to Good-Till-Cancelled order configurations that remain active and eligible for execution during pre-market and after-hours trading sessions alongside normal daily business hours, depending on the specific broker platform utilized. While standard GTC orders typically restrict execution exclusively to regular exchange hours, specialized extended-hours GTC parameters allow pending limit orders to persist across multiple pre-market and post-market sessions until filled or cancelled. Traders utilizing these options must account for wider bid-ask spreads and lower liquidity during off-peak hours.