Carrying a 1DTE overnight means the next morning is decision time. The option now expires today, so it's a 0DTE with one session of time value left — and the open reveals whether your overnight thesis paid.

Read the open first

The gap is your report card. If SPY gapped in your favor, you're likely holding a gift — but the whole dealer map has reset, so read the fresh structure before deciding. If it gapped against you, the thesis is in question. Either way, don't trade the first few minutes' noise; let the open settle.

The three exits

Take the gift: if the gap worked and you're up big, strongly consider taking the profit — you've captured the overnight move, and now the today's theta cliff is a headwind. Scale out into the open's levels rather than holding for perfection. Manage the winner: if there's a case for continuation into a supportive regime, trail a tight stop and let a piece run, but respect the expiration clock. Cut it fast: if it gapped against you and the thesis is broken, take the loss at the open — don't nurse a losing 1DTE through its final expiration day hoping.

The overnight bet is settled at the open. Take the gift, manage the runner, or cut the loser — but don't drift; it expires today.

The discipline

The trap is treating a favorable gap as a reason to get greedy, or an adverse gap as a reason to “wait for a bounce” on an option that's now decaying toward zero all over again. Have the exit plan set before the open. Whatever's left is a same-day option, so all the 0DTE close rules apply for the rest of the session.