This is the difference between the price of a property that is being sold and the price of the property being purchased when someone is moving up the property ladder.
So if a person is selling their property for £100,000 and buying for £150,000 the trading gap is £50,000. Many people moving up the property ladder would prefer to do so in a falling market because although their property is worth less, the one they are trying to buy will have lost a greater value - the trading gap has decreased.
