oversupply

/ˈō-vər-sə-ˌplī/

noun

  1. an excessive supply : an amount of something (such as a good) that is more than is needed or wanted

… if there is an oversupply of herring on a given day, the shrewd fishmonger will lower his price …

verb

  1. to supply (something, such as a commodity) in excess : to provide (someone or something) with more than is needed or wanted

The OPEC nations have been oversupplying crude oil for more than two years, seemingly in an attempt to drive their main competitors—US shale oil and gas producers—out of business.