If two companies are entering a monopoly market, this intervention would likely affect the market structure by potentially breaking up the existing monopoly and creating a more competitive environment. With the entry of these new companies, there would be increased competition for market share, leading to lower prices for consumers and potentially higher levels of innovation and product differentiation. This intervention could result in a shift towards a more competitive market structure, such as an oligopoly or monopolistic competition, depending on the number of firms that enter the market and their market share.
