Which rule provides intermarket price priority for accessible quotations?

The Order Protection Rule is primarily designed to ensure that investors receive the best possible execution of their orders by requiring that trades occur at the best available prices across different markets. Under this rule, a trading venue must protect orders it receives from being executed at a price that is inferior to the best quotes available on other exchanges. This means if there are accessible quotations on other markets that offer a better price, the venue must prioritize those quotes, thereby ensuring fair competition and protecting investor interests.

In contrast, the Access Rule generally pertains to the ability of market participants to access quotes on various exchanges, but it does not specifically mandate price priority. The Sub Penny Rule addresses the pricing increments for quotes, preventing them from being printed in sub-penny increments for certain securities to ensure clarity and fair pricing. Lastly, the Market Data Rules relate to the dissemination and accessibility of market data but do not directly govern intermarket price priority.

Thus, the Order Protection Rule fundamentally supports the principle of intermarket price priority, ensuring that all market participants can benefit from the best available prices across different trading venues.