Kevqas,
Gaps don't always close, but for some reason they have a tendancy to do so. I am not sure of the mechanism, it may be:
1. because everyone is waiting for it to happen so it does; or
2. because of the sudden sp movement that caused the gap results in a temporary buy/sell imbalance and than as the balance averages out, the gap is closed.
I suspect both of the above points work equally to close gaps.
Jim
