This study looks at how different competition strategies affect social welfare in a market where companies are connected vertically. The researchers discovered that in this type of market, when the upstream company supports the downstream firm by offering negative prices for materials, the overall welfare of the society is higher when the companies compete by setting quantities rather than prices. However, setting negative prices is not realistic because it could lead to excessive purchasing by the downstream firm. When a restriction is added to prevent negative pricing, the results can be different, with the price-based competition coming out on top in terms of welfare.