It’s illegal for a market maker to fill an order internally without first attempting to fill in the open market. There are lots of rules and regulations for ensuring a customer’s order follows ‘best execution’ rules. Market makers are also institutions that are allowed to trade in the Dark Pools, which explains not affecting price. So while acting as a market maker, they are not only trading stock for and out of their own inventory but executing transactions for others as well.

Even though WeBull is your broker, they still must route your order to the open market. If they are offering the security at a better price, they are allowed to fill your order however.

Market Makers are important for providing liquidity to the overall market, as without the DMMs and other MMs it would be a lot harder to get your order filled. Market Makers also makes the ‘spread’ of the security (keep in mind we BUY at the ask, and SELL at the Bid while the Market Maker BUYS at the Bid and SELLS at the ask so they also receive an immediate gain in that sense).

As a client with any brokerage, you have the right to ask your brokerage what exchange your order executed on and even who you traded with. They must maintain these records for at least 1 year (the rule I believe is three years do not quote me on this part though)