The problem with regulatory rules, is that are often vague in details. That creates a situation where compliance officers need to side on the conservative side. Regulators have often in the past fined Brokers for details not explicit in the rules. Like they should have known. "CBOE Rule 6.8C, adopted in 2001, prevents market manipulation by limiting the ability of non-Designated Primary Market-Makers to compete on preferential terms in CBOE's automated systems. The rule prohibits members from entering or permitting the entry of orders as principal or agent." The CBOE also allows "Professional Customers" to make two sided markets. According to Frequently Asked Questions (FAQs) on CBOE Regulatory Circular RG16-06, Question 5: Can Professionals place orders on both sides of the market? Answer: Yes. Rule 1.1(ggg) provides that Professionals will be treated in the same manner as broker-dealers for purposes of Rule 6.8C. Under CBOE Rule 6.8C, Prohibition Against Members Functioning as Market-Makers, TPHs may neither enter nor permit the entry of customer orders into the Exchange's electronic Order Routing System if (i) the orders are limit orders for the account or accounts of the same beneficial owner(s) and (ii) the limit orders are entered in such a manner that the beneficial owner(s) effectively is operating as a market maker by holding itself out as willing to buy and sell such securities on a regular or continuous basis. Since Professionals are treated the same as broker-dealers for purposes of Rule 6.8C, their orders are considered to be brokerdealer orders, not customer orders under Rule 6.8C and thus, the restriction does not apply to Professional orders. There are a few things here that I find vague. And I do not know the answer. Do these rules apply to all Option exchanges? Can you bid to open on CBOE and offer to open on AMEX? You still must code your order correctly, which is another challenge. In practice, I expect most brokers will block being on both sides to open for Customer Priority accounts, even if the customer is not placing both orders on the CBOE. They might even apply that to "Professional" orders, as they might not want to code both into their risk checks.