What is the action of creating a monopoly or restricting fair trade in insurance transactions called?

The action of creating a monopoly or restricting fair trade in insurance transactions is best described as an antitrust violation. Antitrust laws are designed to promote competition and prevent practices that restrain trade, such as monopolies or collusion among companies to fix prices.

When entities engage in collusion, they typically work together in secret to limit competition, which can lead to market domination. Boycotting involves refusing to buy from or deal with someone as a form of protest, and while it can impact trade, it does not inherently create a monopoly. Cartel formation refers to an agreement between competing firms to control prices or market supply, which is also linked to antitrust violations but is a more specific mechanism rather than the broader term used in this context.

Therefore, antitrust violations encapsulate the overall illegal actions of creating monopolies and restricting free competition, making it the most accurate answer.