Walmart Inc. is bringing pre-owned watches and collectible trading cards to its online marketplace as the retailer looks to further beef up its e-commerce business and grab more spending from rivals such as eBay Inc. and Amazon.com Inc.

The company is expanding the assortment on its marketplace, which offers merchandise from third-party vendors, to meet customer demand, according to Tom Ward, Walmart’s chief e-commerce officer. The new categories, which also include high-end beauty products, collectibles and other pre-owned products, will help Walmart expand its customer base and drive growth, he said.

It adds to Walmart’s allure, he said, when “they see a brand they weren’t expecting to see or they search for something they are interested in, they find not just a couple of results but hundreds of thousands of results.”

The marketplace is fueling growth of Walmart’s e-commerce business. The Bentonville, Arkansas-based company said in August that its online sales grew 22% in the US during the previous quarter. The number of weekly active customers is also rising and consumers are increasingly paying for quicker deliveries. The company is working to cut costs associated with e-commerce and has assured investors that there’s a path toward profitability.

Marketplaces help Walmart and competitors appeal to online customers by expanding their assortment and price points. Companies can also add income via related services, including advertising and fulfillment. For retailers that are largely brick-and-mortar, marketplaces can also serve as a place to trial new products or those from upstart brands.

Big retailers’ strategies vary: Amazon, which has a marketplace that’s more than two decades old, sells a vast range of products including pre-owned items and collectibles. Target Corp., which teamed up with Shopify Inc. earlier this year, is taking a more curated, selective approach.

Walmart said marketplace sales increased more than 30% for four straight quarters. The total number of sellers on the platform, which the company doesn’t disclose, has risen by double digits. Some categories, such as pet products and beauty, are growing at annual rates of 20% to 30%.

The marketplace has particularly boosted Walmart’s offering of general-merchandise products such as home decor and apparel, and it’s now carrying brands it typically hasn’t sold, from Cartier to Michael Kors. Michael Kors handbags were among the top sellers on the marketplace last holiday season, executives said during Walmart’s annual shareholders week in June.

Consumers are increasingly seeking refurbished electronics as they look for more sustainable, price-conscious options, said Manish Joneja, senior vice president of Walmart Marketplace and Walmart Fulfillment Services, on a call with reporters. The company plans to take additional steps to verify sellers. It also will leverage excitement for collectibles by offering preorders, he added.

Walmart is also starting new offerings for its fulfillment services business that charges sellers for storing and shipping products at its distribution centers. It will now let sellers ship to customers via its fulfillment services, even if the order originated from another website. The business will also handle transportation of goods from Asia to the US.

Walmart is promoting its marketplace with sellers at a summit in San Francisco this week.