Topic · Trading & Microstructure
← All topicsVenues & Regulation
32 articles · 5 checkpoints · 20 deeper reads · 7 reference notes
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Regulation NMS is the 2005 US rule set that ties every stock exchange together into one "National Market System", it's the reason your broker is legally required to get you the best displayed price, no matter which exchange is quoting it.
The National Best Bid and Offer is the single best price across every US exchange, stitched together in real time from a dozen-plus separate venues, it's the reference price nearly every US equity rule is written against.
Europe's answer to Reg NMS isn't a hard rule tied to displayed prices, it's a broader legal duty requiring brokers to take "all sufficient steps" to get clients the best overall outcome, weighing price, cost, speed and likelihood of execution together.
Many retail brokers don't send your order to an exchange at all, they sell it to a wholesale market maker who fills it directly, and pays the broker for the privilege, which is why your "commission-free" trade still generates revenue for someone.
The single print that becomes "today's closing price" isn't the last continuous trade of the day, it's a separate call auction, run after a dedicated order-collection period, that now handles a huge and growing share of total daily volume.
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