The key difference between a Dealing Desk (DD) broker and a Non-Dealing Desk (NDD) broker lies in their order execution model and conflict of interest with traders.

1. Execution Method
DD Brokers (Market Makers): Act as counterparties to client trades, meaning they can take the opposite side of a trade. They may execute orders internally instead of routing them directly to the market.

NDD Brokers (ECN/STP): Route orders directly to liquidity providers (banks, hedge funds) without interference, offering direct market access.

2. Pricing & Spreads
DD Brokers often provide fixed spreads but may widen them during volatility or engage in requoting.

NDD Brokers offer variable spreads that reflect real-time market conditions, usually tighter but with commissions.

3. Conflict of Interest
DD Brokers profit from client losses (if they take the opposite side), leading to concerns about price manipulation or stop hunting.

NDD Brokers earn only from commissions or markups, eliminating conflicts since they don’t trade against clients.

4. Best for Which Traders?
DD Brokers suit beginners due to fixed costs and no commissions.

NDD Brokers are preferred by scalpers and professionals for transparency and faster execution.

In summary, DD brokers control pricing and execution, while NDD brokers offer a more neutral, market-driven trading environment.