Hector Rivas co-founded ThriftBooks alongside Daryl Butcher and Jason Meyer in Seattle, Washington. Rivas became chief executive officer when the company was struggling and in debt. Under his leadership ThriftBooks became profitable and grew into Amazon.com’s largest third-party bookseller and one of the largest used book retailers in the United States, reaching more than $150 million in annual revenue.

Rivas built the company’s procurement model by negotiating directly with national thrift store chains and charitable organizations including the Salvation Army, Goodwill, and Value Village to purchase inventory by the truckload from their distribution centers. He later pioneered a library profit-sharing program that gave institutions a financial return on surplus inventory.

Rivas also developed two additional business lines in the company’s early years. Unsold inventory that had previously been discarded was redirected to paper recycling partners who paid ThriftBooks by the ton, converting a disposal cost into a new source of revenue. He also established an overseas bulk book business, sorting unsold titles by category and selling them by the container load to international buyers.

In 2009 ThriftBooks purchased more than 41 million used books that would otherwise have gone to landfills. The following year the United States Environmental Protection Agency recognized the company as a WasteWise Partner. Rivas served as chief executive officer for ten years, from 2004 to 2014.