Now in its sixth year, the Amazon Accelerate 2025 seller conference that I recently attended brought together thousands of marketplace sellers and was full of vibrant energy. Globally, gross merchandise value for online marketplaces now tops $3 trillion, per Forrester’s 2025 Online Marketplace Tracker, Global.

Online marketplaces fill significant need for consumers. As just one example, more than three out of five online adults in the US say that online marketplaces have helped them find items for sale online that they may not have found otherwise, per Forrester’s Retail Topics Insights 1 Survey, 2024. And around half said that they trust a purchase through a familiar online marketplace even if the retailer selling the item isn’t familiar to them.

Here are my key takeaways from the Amazon Accelerate event:

  • Agentic AI makes Seller Assistant proactive. Amazon’s Seller Assistant now uses agentic AI to reason, plan, and act with a seller’s permission. It monitors inventory levels, flags slow‑moving products, recommends markdowns or removals, and even schedules shipments with seller approval. These capabilities help reduce both excess inventory costs and out-of-stock situations. The tool also monitors a seller’s account status to surface potential issues such as safety violations and guides sellers through compliance paperwork using generative AI. In an interview, Amazon VP Dharmesh Mehta said the agent was trained on 25 years of shopping data to help merchants navigate volatile demand and tariff‑driven disruptions.
  • Expanded supply chain services reduce lead times and cut costs. Supply Chain by Amazon continues to expand, now offering automated global warehousing and AI-powered customs clearance. Amazon unveiled Global Warehousing and Distribution so sellers can store inventory near manufacturing sites and then replenish US fulfillment centers, which it asserts that it can achieve up to seven days faster. Amazon now uses generative AI to prepopulate customs forms, saying that this can cut sellers’ paperwork time by more than half.
  • Multichannel fulfillment deals expand Amazon’s reach. After enabling fulfillment for sellers on sales channels like eBay, Etsy, Temu, and TikTok Shop, Amazon Multi-Channel Fulfillment is now expanding to support sellers using Walmart, Shopify, and SHEIN. Sellers can maintain a single inventory pool and achieve real‑time inventory sync, thereby lowering out‑of‑stocks and improving turnover. According to Amazon, sellers using Fulfillment by Amazon and Multi-Channel Fulfillment see 19% fewer out-of-stock rates and 12% better inventory turnover.
  • AI‑powered Creative Studio promises faster, more effective ads. With agentic AI integrated into Creative Studio, sellers can now generate professional-quality ads through simple conversational prompts. This capability dramatically reduces ad creation time and improves performance. According to Amazon, one seller saw a 338% increase in click-through rates and 121% return on ad spend.

At Forrester, we expect a continued shift in retail market share toward Amazon and Walmart over the next five years as both companies invest in AI and machine learning, automation, and customer experience. For example, Walmart also continues to develop agentic AI tools tailored to retail-specific tasks and is investing significantly in supply chain transformation. Both Amazon and Walmart are further growing alternative sources of revenues and profits such as retail media.

If they’ve not already started, global marketplaces must analyze how to integrate agentic AI into their own seller ecosystems and to streamline compliance and logistics. They should benchmark against innovations from market leaders to identify gaps and help their sellers fulfill orders quickly and reliably. Smaller retailers will need to invest to achieve significant differentiation in terms of service, assortment, and store/online experience.

If you are a Forrester client and would like to learn more, please schedule an inquiry or guidance session with me!