ThredUp moves marketing upstream with AI-powered forecasting
ThredUp, the online resale platform, is using AI for marketing operations to shift from reactive spending to predictive budget allocation. The company's head of marketing, Kristen Brophy, said the shift has made her team more effective partners to the finance department.
ThredUp works with incrementality testing and media mix modeling vendors to forecast returns on marketing spend. The company feeds customer lifetime value predictions back into Meta and Google, enabling lifetime value targeting at scale.
Moving further up the funnel
When Brophy joined ThredUp in 2024, the company concentrated almost entirely on lower-funnel channels: Google Performance Max, product listing ads, and Meta. As the business grew, that strategy became limiting.
ThredUp now invests in mid- and upper-funnel marketing to build demand. The company has tested new channels including affiliate partnerships, Pinterest, and TikTok Shop. AI forecasting tools help justify these less immediately measurable investments to finance teams.
What works and what doesn't
ThredUp evaluates new channels using four criteria: Are customers acquired? Is the acquisition cost competitive? Are those customers valuable? Can the company scale the spend?
TikTok advertising hasn't worked. Brophy said the company "cannot scale our spend effectively with static or video advertising on TikTok." TikTok Shop, however, has succeeded-specifically through affiliate partners promoting ThredUp's Clean Out Kit, a service that lets customers mail items to ThredUp for resale.
Affiliate models work better because "everybody has skin in the game," Brophy said, improving outcomes for influencers, the business, and customers.
The persistent challenge
Brophy identified one problem AI hasn't solved: proving the value of brand-building investments against quarterly targets. Long-term marketing bets require patience that quarterly earnings reports don't allow.
"I don't think marketers have the luxury anymore of being like, 'We should just [invest in something] because it's cool,'" Brophy said. AI tools help make the case, but they don't eliminate the tension between brand building and immediate returns.
For marketing managers facing similar pressures, ThredUp's approach demonstrates how forecasting and incrementality testing can support investment decisions across the full funnel.
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