A gap might or might not happen, for the tests I've done, when it DOES happen, it WILL close. There is a tendency of about 60-70% of it closing on the day it occurs, with a 30-40% tendancy of it closing the day after it happens, and a 10% chance that it closes on the third day .... if it doesn't close that third day, the market tends to move in the direction of the gap for a week or month or so, before turning to slowly, steadily, close the gap. Interestingly, even the recent sell-off causing a nasty bear market, included a gap close of a gap which was left open a few years back. (more interesting was a comment from another forumite that the gap was history, forgotten about ... yet it closed). The reasons why gaps close are all very interesting, for those who want to google it. Gaps happen in RSA, because our market closes, unlike the US. If we close, and the rest of the world rallies or falls while we're closed, we open the following day substantially higher or lower than we closed. This is the GAP. Through trading behaviours between sellers, buyers, and those that held over-night, fear and greed causes the close. A close on the day is less likely when there is a "market moving event" like a rate cut, a pressidential assasination, and the like. On this forum, there are not really profitable low risk products to trade on the gap. But being aware of the phenomena can help substantially when you are looking to enter or exit a trade on the day.