If an investment manager discusses a proprietary strategy prematurely, what might they violate?

A premature discussion of a proprietary strategy by an investment manager can indeed lead to the violation of multiple standards established by the CFA Institute.

First, with respect to Standard II(A), which addresses Material Non-Public Information (MNPI), sharing a proprietary strategy before it is fully developed or implemented could lead to the disclosure of information that is not yet available to the public and could significantly influence an investor's decision-making. Such a breach could result in unfair advantages for certain clients over others or lead to market manipulation, highlighting the importance of maintaining confidentiality around proprietary strategies until they are publicly disclosed or officially implemented.

Additionally, Standard III(B) on Fair Dealing emphasizes the need for investment professionals to deal fairly with all clients in relation to the investment recommendations and actions they take. If a proprietary strategy is discussed prematurely, this could lead to certain clients having access to information not available to others, which is inherently unfair and violates the principle of offering equal treatment in the distribution of investment-related information.

Thus, discussing a proprietary strategy too early can violate both the standards regarding Material Non-Public Information and Fair Dealing, making the answer well-founded.