SET-listed stocks behave differently from 24-hour FX markets. The session gap, the call auction, and the lunch break create structure that looks like support on a daily chart but acts as noise on an intraday read.
After reviewing hundreds of participant charts, three invalidation errors recur.
Error 1: Using yesterday's close as support
The prior close is a reference price, not a structural level. Stops placed a few ticks below yesterday's close on an intraday long often sit inside the opening range — especially on earnings days or after holiday-thinned sessions.
Correction: Mark the low of the opening 15-minute range or the pre-lunch session low, whichever is further from entry and still logical for your timeframe.
Error 2: Ignoring the lunch break gap
Charts that span the 12:30–14:00 break sometimes show a visible "step." Traders draw trendlines through the step, placing stops on the wrong side of it.
Correction: Treat the break as a session boundary. Mark structure within the morning session separately from the afternoon session.
Error 3: Sizing off full daily range on a scalp
A day trader marks a stop beyond the daily low while targeting a 0.5% move. The R-multiple looks attractive on paper because the daily range is wide — but the stop is irrelevant to the scalp timeframe.
Correction: Invalidation must match the trade duration. A 20-minute scalp uses the 20-minute structure, not the daily wick.
Workshop exercise
In the flagship session, we project an SET chart from the prior week and ask each trader to mark invalidation independently. Group review typically reveals at least two of these three errors in the room. Comparing placements side-by-side is often the most cited "aha moment" in session feedback.
If you trade SET stocks and plan to attend, bring one intraday chart and one swing chart — the errors differ between them.