sell side noun2 •The sector of the finance industry that sells products such as stocks, bonds, and mutual funds to investors.The sell side exists only because the buy side trades before we can understand when the sell side is profitable. — 2003 •A model of e-commerce in which the seller hosts an application that enables buyers to purchase their products.Shopping on the Internet at Web sites such as amazon. com and toysrus.com are examples of the sell side model. — 2004 formssell sides