Capitalism was an economic system based on the production of commodities for profit and the existence of private property, typically in its most advanced form involving private ownership of the means of production by individuals and corporations competing in a free market. A version of the Doctor from an Alternate universe described it as such; "Some people win; most lose all they had." (AUDIO: The Emporium At The End), Although there was disagreement as to whether or not this descriptor was also fairly applicable to the version of Captalism in operation in N-Space, as well, with various incarnations of the "prime" Doctor displaying different opinions on this; for instance the Seventh (PROSE: Closing the Account) and Twelfth (TV: Oxygen) Doctor thinking it did, with the Thirteeth denying at least that such problems were necessarily inherent to the system. (TV: Kerblam!)
Capitalism was often characterised by a lack of regard to the lives of others. Ganymede Systems began to not providing oxygen in space stations and forced people to buy it via smart suits. They also began killing workers when they hadn't been productive enough and brought into new workers. However, thanks to the Twelfth Doctor, a rebellion was started and Ganymede Systems was overthrown. According to the Doctor, the incident 'about wrap[ped] it up for capitalism.' (TV: Oxygen)
The Eighth Doctor was assumed to be a capitalist by several people in Spain. Fitz Kreiner branded Anji Kapoor a "capitalist pig" who was in turn surprised by how similar career communists and career capitalists were.
While fighting in the Spanish Civil War, Bob Edwards used a megaphone to shout out lengthy political arguments about the capitalist system. (PROSE: History 101)