It’s called the Robinson-Patman act. The legislative purpose was to amend the inadequate Clayton Act so as ". .. to curb and prohibit all devices by which larg

It’s called the Robinson-Patman act. The legislative purpose was to amend the inadequate Clayton Act so as ". .. to curb and prohibit all devices by which large buyers gained discriminatory preferences over smaller ones by virtue of their greater purchasing power." [1] It’s now interpreted based upon cost of manufacturing, so the FTC has this Q&A [2]: > Q: I operate two stores that sell compact discs. My business is being ruined by giant discount chains that sell their products for less than my wholesale cost. What can I do? A: Discount chains may be able to buy compact discs at a lower wholesale price because it costs the manufacturer less, on a per-unit basis, to deal with large-volume customers. If so, the manufacturer may have a "cost justification" defense to the differential pricing and the policy would not violate the Robinson-Patman Act. Note as [1] describes, this act was done in reaction to chains causing much distress. The nature of manufacturing changed, and as the notion from the 60s/70s that consumer pricing was the most important trait in anti-trust law, so enforcement stopped and now we have chains everywhere. [1] https://scholarship.law.stjohns.edu/cgi/viewcontent.cgi?article=3621&context=lawreview https://scholarship.law.stjohns.edu/cgi/viewcontent.cgi?arti... [2] https://www.ftc.gov/tips-advice/competition-guidance/guide-antitrust-laws/price-discrimination-robinson-patman https://www.ftc.gov/tips-advice/competition-guidance/guide-a...