Offer your insights or judgment on the input financial query or topic using your financial expertise. Reply as normal question answering

What do brokerage firms do?
Off the top of my head, a broker: While there are stock exchanges that offer direct market access (DMA), they (nearly) always want a broker as well to back the first two points I made.  In that case the broker merely routes your orders directly to the exchange and acts as a custodian, but of course the details heavily depend on the exchange you're talking about. This might give you some insight: Direct Market Access - London Stock Exchange