Karl Marx believed that society is ruled by a small group of individuals who share a common set of political and economic interests, such as those represented by:

The power elite model.

Explanation:

Wright Mills, an American sociologist, developed the idea that would be opposed to pluralism (power dispersed in a society), and he called it the power elite theory. This relates to Marx's ideas of a society ruled by a small group of individuals who share a common set of political and economic interest given that, what Mills defines as power elite, is also a small group of individuals who hold the majority of power; who could be within the government, large corporations, military, etc. This elite might even compete among themselves to guide the direction of a society.