Members must not engage in practices that distort market prices or volumes with the intent to mislead participants according to which standard?

The standard that members must adhere to, which prohibits engaging in practices that distort market prices or volumes with the intent to mislead participants, is known as Market Manipulation. This standard emphasizes the responsibility of professionals to maintain fair and transparent markets by avoiding deceptive practices that could mislead investors and distort the price discovery process.

Market manipulation involves actions such as creating artificial demand or supply to influence market prices, which undermines the integrity of the marketplace and can lead to significant harm to other investors. Upholding ethical standards in trading practices is crucial for maintaining trust and confidence in the financial system.

The other standards listed, while important in their own rights, focus on different aspects of professional conduct. Professionalism pertains to the overall ethical demeanor expected from members, while Independence and Objectivity emphasize the need for professionals to remain unbiased and free from conflicts of interest. Material Nonpublic Information deals specifically with the use of insider information, which is also critical but does not directly address the concern of manipulating market prices.