Two principle expressions of capitalism in An Ideal Husband involve Lord Chiltern and Lady Cheveley. In the first instance, Lord Chiltern confesses to Lord Goring that in his youth he followed the materialistic and capitalistic theory of accumulation of wealth and power by any means espoused by Baron Arnheim. Seduction into this theory led Chiltern to sell a state political secret for personal gain.
Chiltern's rationalization is that even though he was of a good family, he was poor and hence would not be able to get ahead in accord with his political ambitions. In Chiltern's youthful mind, and perhaps present mind, his "folly" paved the way for a greater good. Goring reminds Chiltern that his action wasn't "folly," it was rather a criminal act of an "fairly ugly and very grave" nature.
Mrs. Cheveley embodies the second instance of the expression of capitalism. She knows Chiltern's secret and is extorting him with it in order to reap monetary gain on a grand scale through mechanization and intrigues at the government level relating to a capitalist enterprise in South America.