Imperialism is a stage of capitalist development

Imperialism is a stage of capitalist development with five simultaneous features:

1) Concentration of production and capital has led to the creation of national and multinational monopolies - not as understood in liberal economics, but in terms of de facto power over their enormous markets - while the "free competition" remains the domain of increasingly localized and/or niche markets:

Free competition is the basic feature of capitalism, and of commodity production generally; monopoly is the exact opposite of free competition, but we have seen the latter being transformed into monopoly before our eyes, creating large-scale industry and forcing out small industry, replacing large-scale by still larger-scale industry, and carrying concentration of production and capital to the point where out of it has grown and is growing monopoly: cartels, syndicates and trusts, and merging with them, the capital of a dozen or so banks, which manipulate thousands of millions.

At the same time the monopolies, which have grown out of free competition, do not eliminate the latter, but exist above it and alongside it, and thereby give rise to a number of very acute, intense antagonisms, frictions and conflicts. Monopoly is the transition from capitalism to a higher system. (Ch. VII)

[Following Marx's value theory, Lenin saw monopoly capital as plagued by the law of the tendency of profit to fall, as the ratio of constant capital to variable capital increases. In Marx's theory only living labor or variable capital creates profit in the form of surplus-value. As the ratio of surplus value to the sum of constant and variable capital falls, so does the rate of profit on invested capital.]
2) Industrial capital as the dominant form of capital has been replaced by finance capital (repeating the main points of Rudolf Hilferding's magnum opus, Finance Capital), with the industrial capitalists being ever more reliant on finance capital (provided by financial institutions).
3) The export of the aforementioned finance capital is emphasized over the export of goods (even though the latter would continue to exist);
4) The economic division of the world by multinational enterprises, and the formation of international cartels; and
5) The political division of the world by the great powers, in which the export of finance capital by the advanced capitalist industrial nations to their colonial possessions enables them to exploit those colonies for their resources and investment opportunities. This superexploitation of poorer countries allows the advanced capitalist industrial nations to keep at least some of their own workers content, by providing them with slightly higher living standards.

Vladimir Lenin