On exchange has a particular significance in relation to IG's platform. Here, we define on exchange in general investing.
On exchange is a term used to mean that a trade is taking place directly on an order book. It differs from at quote, which is a trade made at the price quoted by a market maker.
DMA, or direct market access, is one way of trading on exchange: allowing you to see the various prices offered on an exchange and identify which prices are best for you.