When trading, DMA stands for direct market access. It’s a way of placing trades that offers more flexibility and transparency than traditional dealing (which is usually referred to as OTC, or over-the-counter). It’s suitable for advanced traders.
With DMA, investors place trades directly on the order books of equity exchanges. DMA traders can see the orders directly on the books of the exchange that they are dealing with, and are charged on a commission basis instead of via the spread.
DMA can be a good way for advanced traders to get a more comprehensive view of the market, and see the best possible prices available. However there are also risks and complexities involved. It is often referred to as Level 2 (L2) trading.