The rectangle is the least important part of an order block. What matters is the reason a rectangle could mean anything at all: somebody traded a lot of size in a small range and then price left. The block is a claim about what was left behind. Read it as inventory, and most of the folklore around it falls away.
What actually happens in the candle
A large participant cannot buy the size they want at one price. They accumulate: resting bids, some aggressive lifts when the offer thins, more bids lower if price dips. The footprint of that work is a range where volume is heavy and price does not go far. When the position is complete, or when the other side gives up, price moves. The last down candle before the move up is the block in the textbook, but the textbook is describing a shape. The mechanism is the unfinished business inside it: orders that did not fill, a position that was built cheaper than the current price, and a participant who now has a reason to defend the area.
That defence is the whole edge. If the position is real and still open, a return to the range meets bids again, because the holder would rather add at their average than see it fail. If the position was closed on the way up, or was never large to begin with, there is nothing there and the rectangle is a memory of nothing.
Why most blocks are empty
Drawn from bars, every impulsive move produces a candidate block, so charts fill with them and the one that works is remembered. Three things separate a block with inventory from a shape:
- Volume relative to the move. Heavy trade with little progress is accumulation. Light trade with a big move is a vacuum, and vacuums do not hold.
- Who initiated. If the range was built by aggressive selling that failed to push price down, someone was absorbing it. If it was built by aggressive buying that did push price up, the buyers are already in and have less reason to return.
- What price did afterwards. A move that leaves an imbalance behind, trading through prices with almost no volume, was in a hurry. A move that grinds away spent its inventory on the way.
Mitigation is not invalidation
A block that is touched and holds has been tested, not spent. The holder defended it once, which is evidence they are still there. A block that is traded through and then reclaimed is a different animal: the original inventory was run over, and whoever bought the reclaim is a new participant with a new average. Treating the two as the same "retest" is how the concept got its reputation for working half the time.
What we do with this
Our order-block engines rank a candidate by the flow that built it, not by its shape, and they mark a block as broken the moment the market trades through it on volume. The rule costs some pretty rectangles. It also means the ones that stay on the chart earned it, and that is the only kind worth acting on.