aftermarket

[af-ter-mahr-kit, ahf-]

noun

the market for replacement parts, accessories, and equipment for the care or enhancement of the original product, especially an automobile, after its sale to the consumer: The company holds a large share in the automotive radio aftermarket.
any additional market created by a product after the primary market: Television is the perfect aftermarket for old movies.
Stock Exchange. secondary market.

Origin of aftermarket

First recorded in 1935–40; after + market

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

1940, American English, of automobile parts, from after + market.