The purchase and sale of shares of a company by its own promoters is commonly referred to as "insider trading." Insider trading occurs when individuals, such as company insiders (like promoters, executives, or employees), trade the company's securities based on material non-public information, giving them an unfair advantage in the market.

Promoters are individuals who have a significant stake in the company, often involved in its management and decision-making. If promoters engage in buying or selling the company's shares based on undisclosed information that could impact the stock price, it is considered insider trading and is generally illegal.

Regulators and stock exchanges have strict rules and regulations to prevent insider trading and maintain the integrity and fairness of financial markets. Insiders are required to adhere to disclosure requirements and refrain from trading the company's securities based on material non-public information. Violations of insider trading laws can lead to legal consequences and penalties.