Over the past four years, Christine Su has expanded AI-powered recommendations on eBay and tackled safety issues at Twitter (now X), taking on knotty ethical concerns over generative AI and free speech on social media platforms.
But there was a time when Su found herself drawn to the pastoral life, far removed from the dynamics of social media. In her twenties, after a few years in consulting and private equity, she quit her job. “I burned out pretty quickly,” says Su, who uses she/they pronouns and currently oversees strategy for personalized recommendations at eBay. To recover and reset, they decided to spend a summer working on a dairy farm in Japan. “That actually was a very important, seminal experience to know that I don’t function without mission and purpose in my work,” Su says. “As long as we’re all in this corporate capitalist model, how do we use it—and the power that it can drive—for good?”
After going to business school and completing a master’s degree in land use and agriculture, Su started a software analytics startup called PastureMap to help incentivize farmers to embrace sustainable and regenerative practices by giving them a digital platform to manage their grazing land with. By the time PastureMap became profitable, managing six million acres of grazing land across the world, Su concluded that the company had gone as far as it could without more sweeping legislative changes. “You eventually do need collective action; you do need regulatory intervention,” she says. “The next step change would have [been] to pass laws. And I was like, I don’t know if I want to be a lobbyist for the next 20 years.”
They were also looking to pivot, after seven years of running a climate startup. “If you’ve been in the climate space, especially if you do any climate justice work, the burnout rate is super high,” Su says. Once again, they felt like they needed to take a breather.
So she sold PastureMap and took a job at Twitter, where she was tasked with addressing some of the platform’s most intractable issues related to content moderation and conversational safety. “I think I really am attracted to big, hairy, systemic problems that are likely to take a lifetime and a lot of collective action to untangle,” Su says. In a meta twist, she found herself on the receiving end of harassment on Twitter not long after she joined the company, when the right-wing site Breitbart picked up a story about her appointment to the role.
During their time at Twitter, Su says the company empowered users to exercise more control over their experience on the platform. One such feature gave users the ability to limit replies on tweets. Twitter also rolled out Safety Mode, which enabled users to automatically block accounts that used “potentially harmful language.” Su says their team at Twitter—and now, at eBay—was always grappling with difficult questions about how to balance the competing interests that were inherent to the platform.
“eBay is a marketplace of everything the world has to offer,” Su says. “Twitter is a marketplace of ideas. How do you do that without hatred and misinformation and racism running rogue—things that are repugnant and actually cause real world harm? How do you balance speech and a marketplace of ideas against harm, especially to the most marginalized communities?” As someone who is both Asian and nonbinary, Su also felt their point of view was invaluable, especially given they had experienced that harm firsthand. “It’s absolutely critical for folks with these perspectives to be in the rooms where the product is created,” Su says.
In 2022, however, after Elon Musk’s acquisition of Twitter had been set into motion, Su made the jump to eBay. In some ways, she says, joining eBay was a callback to her time working in the climate space and building PastureMap, which had advocated for a circular-economy approach to farming. “eBay is, low-key, one of the biggest circular-economy players in the world—the original one,” she says of the company, which has been in the resale business for nearly 30 years. “But we’d like to be less low-key about it.” Su was also passionate about small businesses, which she says are the “lifeblood” of eBay.
The global secondhand market crossed $197 billion in 2023 and is projected to hit $350 billion within four years, according to a recent ThredUp report. As the resale market has exploded in recent years, eBay has strived to improve the user experience for buyers and sellers alike, by finessing its matching algorithms. Since stepping into her role 17 months ago, Su has been a key player in those efforts, overseeing recommendations that are powered by AI and machine learning. “It’s a matching game,” she says. “There are millions of buyers, and there are millions of sellers on eBay. The sellers are trying to get through the noise to find their ideal buyers. And then the buyer is like, ‘I’m looking for combat boots—do you know my style?’”
eBay uses hundreds of algorithms to surface the listings that will be most appealing to buyers. More recently, Su’s team has been harnessing generative AI technology to give users more transparency into why they are being shown certain items. “Now, the AI is actually explaining to you why it made that recommendation,” Su says. (This feature was recently launched for sneakers.)
In April, eBay introduced Shop the Look, an in-app addition aimed at fashion lovers: The new section uses generative AI to recommend select items based on their shopping and browsing history on the platform. Su says the AI technology powering the feature will “gradually tailor to your individual style,” and move beyond curated trends. “We are thinking about understanding your taste profile,” she says. Over the past year, Su was also responsible for launching an Explore page, an AI-driven recommendation feed (though it is currently only available in the U.K.) “Shopping should be an infinite feed that is dynamically learning about you all the time,” Su says. “So we finally did that.”
On the seller side, another recent addition—which eBay has dubbed the “magical” listing tool—will simplify the process of posting items to eBay by using generative AI to fill in the details of a listing based on a photo. “Every minute for a small business owner counts,” Su says. “You’re listing stuff in your garage or maybe in a warehouse that you’ve rented with other people.”
As of February, Su’s purview has also grown, making them the head of eBay’s homepage and My eBay, where users can track their buying and selling activity, along with saved items and sellers they follow. The move is a reflection of Su’s vision for how eBay can further customize the user experience across the platform. “We think we could personalize the front door of eBay,” Su says. “So now the AI team is merged with the homepage team and the My eBay team. Instead of eBay being this static experience, I think you’re going to see an acceleration of us being a lot more personalized from the get-go. We’re going to try to get to know you.”
While Su is passionate about the potential for AI to transform the eBay experience, they are also committed to maintaining a “responsible AI framework” for that work. “AI desperately needs ethicists, philosophers, and people who are asking the moral questions of not just can we do this, but should we do this?” Su says. (Last year, eBay announced that the company had set up an Office of Responsible AI.)
As the resale market has exploded—especially in the fashion space—eBay is up against its fair share of competitors. But Su says eBay sees itself as a pioneer in recommerce and believes the company can continue to carry that torch. “That’s a net good for the world,” she says of the increased competition. “Everyone loves thrifting, and it’s just the right thing to do. We want to remove barriers to people actually getting stuff out of their closet.” Su pauses, then quips, “I am an advocate of being out of the closet in every way.”
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