0DTE Options: Why the Textbook Payoff Diagram Lies to You
The chart everyone learns is the wrong chart
Every options course starts with the same picture: a payoff diagram at expiration, a bent line showing profit and loss versus where the stock ends up. That diagram is correct — for the moment of expiration. It tells you nothing about the six-and-a-half hours before that, which for a 0DTE (zero days to expiration) trade is the entire trade. The whole game is the intraday race between theta banking premium for you and gamma exposure growing large enough to erase it in one bad print.
Theta doesn't decay at a constant rate
A short at-the-money straddle opened at 9:30 does not lose value in a straight line through the day. Early in the session, with hours of time still on the clock, decay is slow. By early afternoon, the same position is bleeding value far faster per hour — the classic 0DTE shape is slow-then-vicious, not linear. OptionScope's 0DTE Modeler plots this explicitly: a decay curve alongside dollars-burned-per-hour bars, so the peak-burn hour is visible instead of assumed.
Gamma grows while theta is paying you
Here's the trap: the same passage of time that's banking theta for a short premium seller is also making gamma larger. Gamma for an at-the-money option peaks in the final hours before expiration — by the close, it can be an order of magnitude larger than it was at the open. That means the exact same size stock move does far more damage to a short position late in the day than it would have at 9:30, even though more theta has been banked to absorb it.
The result is a "toxic corridor": a price range around spot where banked theta still exceeds the gamma loss from an instant move. That corridor is razor-thin at the open (no theta banked yet, so any move hurts) and widens through the day as premium burns — but because gamma is growing so much faster, a break late in the session can still be far more violent in dollar terms than an equivalent break at the open.
Straddle or strangle, the physics are the same
Everything above applies whether you're modeling a same-strike straddle or an OTM strangle — the strangle just starts with a wider toxic corridor (and a smaller credit) since both legs begin further from the money. OptionScope's 0DTE Modeler lets you split the call and put strikes independently for exactly this reason, plus model the next couple of real expiries, not just the nearest one, and size a hypothetical position to a dollar risk budget using a stop-loss multiple of the credit received.
Rich or cheap versus what actually happens
One more real-data check worth running before any 0DTE trade: how does today's credit-implied move compare to what the stock has actually delivered on a typical recent day? The 0DTE Modeler pulls the stock's real daily candle history to show the average realized day-range over the last ~20 sessions next to today's implied move — a fast way to see if premium seems rich or cheap relative to how the stock actually behaves, not just what today's IV says.
Try the model yourself in the 0DTE tab (Pro), or brush up on the underlying Greeks first in the glossary.