---
title: Market Volatility & The Trust Playbook: Navigating Fraud in Two-Sided Marketplaces
source_page: https://www.sardine.ai/media/fraudology/episodes/marketplace-fraud-prevention
canonical: https://www.sardine.ai/media/fraudology/episodes/marketplace-fraud-prevention
format: text/markdown
date: 2026-07-15T14:00:00.000Z
description: Marketplace fraud prevention becomes challenging when prices shift fast. Buyer fraud, seller abuse, chargebacks, and weak policies can erode trust…
---

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# Market Volatility & The Trust Playbook: Navigating Fraud in Two-Sided Marketplaces

**Published:** 2026-07-15T14:00:00.000Z

Marketplace fraud prevention becomes challenging when prices shift fast. Buyer fraud, seller abuse, chargebacks, and weak policies can erode trust…

Welcome back to Fraudology.
In this episode, I’m sitting down with Mark Porteous, a longtime leader in e-commerce fraud and trust who knows two-sided marketplaces from the inside out. Mark spent nine years at StockX, where he started in customer support before building the company’s fraud program from the ground up. And honestly, that is one of the best ways to learn marketplace fraud prevention because you see the customer complaints, the chargebacks, the seller issues, the account problems, and the policy gaps before anybody has officially decided they belong to a fraud team.
We get into what makes online marketplace fraud so different from traditional e-commerce. In a standard retail transaction, the merchant controls the inventory, the pricing, and fulfillment. In a two-sided marketplace, the platform may be trusting one person to sell, another person to buy, and sometimes a third person to deliver the product. Every additional participant creates another identity question, another fraud vector, and another opportunity for marketplace scams or policy abuse.
The deeper theme of this episode is market volatility fraud. Prices can change dramatically because of a sports result, a viral release, an artist announcement, a celebrity event, or a sudden shortage. When that happens, legitimate customer behavior changes, but fraudulent behavior changes too. Sellers may decide not to fulfill because they can resell the item for more. Buyers may file friendly fraud chargebacks after prices fall. Stolen cards may be used to purchase high-demand inventory. And risk models that normally work well can suddenly start treating good customers like fraudsters.
Marketplace fraud prevention cannot stay on autopilot. Fraud leaders need strong policies, clear escalation playbooks, reliable fraud intelligence, and real collaboration with vendors, data teams, customer support, marketing, product, and leadership.
What you’ll hear in this episode:
How Mark moved from customer support into building a marketplace fraud program from the ground up.
Why two-sided and multi-sided marketplaces create more complex identity, payment, seller, and fulfillment risks.
How marketplace pricing volatility can trigger seller non-fulfillment, policy abuse, first-party fraud, and chargebacks.
Why World Cup ticket pricing is a real-time example of market volatility fraud.
How friendly fraud can increase when buyers repurchase the same item after its secondary-market price drops.
Why fraud models and vendor strategies cannot be left on autopilot during high-demand events.
How approval rates, false declines, fraud risk scoring, and card-not-present fraud need to be balanced during sudden demand spikes.
Why fraud leaders need playbooks, policy enforcement, and clear escalation paths before an unexpected event happens.
How to work with marketing, product, growth, finance, customer support, and security without becoming the team that says no to everything.
Why strong fraud storytelling must always be supported by fraud analytics and measurable business impact.
You should listen to this episode if you:
Work in marketplace fraud prevention, trust and safety, fraud operations, or fraud risk management.
Manage buyer fraud, seller fraud, marketplace chargebacks, seller verification, or payment fraud prevention.
Work for a ticketing, sneaker, collectible, resale, delivery, or multi-sided marketplace.
Need a better approach to fraud monitoring during major events, product releases, shortages, or pricing spikes.
Want to improve collaboration between fraud, customer support, product, growth, marketing, finance, and security teams.
### Episode notes & key takeaways
Marketplace fraud prevention starts with understanding every side of the transaction
One of the biggest differences between traditional e-commerce and a marketplace is the number of people the platform has to trust.
In a two-sided marketplace, there is a buyer and a seller. In a multi-sided marketplace, there may also be a restaurant, driver, courier, service provider, or another participant involved in completing the transaction. Every additional participant creates another identity question, another fraud vector, and another opportunity for marketplace scams, marketplace account fraud, or policy abuse.
That is why seller identity verification and Know Your Seller, or KYS, controls matter so much. But identity alone does not solve everything. A real buyer and a real seller can still collude. A legitimate seller can still manipulate fulfillment when a price changes. A long-term buyer can still file a friendly fraud or first-party fraud claim when they regret a purchase.
Marketplace fraud detection has to look beyond whether an identity is technically valid. It also needs to evaluate behavior, transaction context, prior history, pricing changes, relationships between accounts, and whether the activity makes sense for that specific marketplace.
That applies across online marketplace fraud, resale marketplace fraud, sneaker marketplace fraud, collectible marketplace fraud, and other high-demand environments where buyer and seller incentives can shift quickly.
Market volatility creates fraud and abuse opportunities on both sides
The World Cup ticket example in this episode shows exactly how marketplace pricing volatility can affect buyer and seller behavior.
A seller may agree to sell a ticket for $1,700. Then the team wins, demand increases, and that same ticket is suddenly worth $2,500. If the marketplace does not require immediate fulfillment, the seller may decide it is financially worthwhile to cancel the original transaction, pay a non-fulfillment fee, and resell the ticket for more.
That is policy abuse, even if the seller is a real person and the ticket is real.
The buyer is left with a refund, but that may not solve the actual problem. They may have already purchased airfare, booked a hotel, traveled to the event, and planned the entire trip around having those seats. Telling them to repurchase the same ticket for another $1,000 does not preserve trust.
The opposite can happen too. A buyer may purchase a ticket for $3,000 and then watch the market price drop to $1,500. They may file a chargeback, claim they did not make the purchase, and then repurchase at the lower price.
That introduces:
Friendly fraud.
First-party fraud.
Chargeback prevention challenges.
Card-not-present fraud exposure.
Policy enforcement questions.
Customer trust problems.
These are not isolated fraud events. They are predictable consequences of market movement, weak policies, delayed fulfillment, and misaligned incentives.
Fraud intelligence and monitoring cannot stay on autopilot
When pricing, demand, and transaction volume move quickly, fraud teams need enough fraud intelligence to understand why.
A spike in order volume does not automatically mean there is a fraud ring. A jump in average order value does not mean every large order should be declined. A sudden increase in international traffic may be completely legitimate during a global event.
At the same time, real payment fraud can hide inside that surge.
That is where fraud monitoring, fraud analytics, fraud risk scoring, fraud detection models, and behavioral context become essential. Teams need to understand whether they are seeing:
Genuine changes in demand
Stolen card activity
Marketplace account fraud
Coordinated buyer and seller behavior
Promotion abuse
Limited release fraud
High-demand product fraud
Fraud detection models creating unnecessary false declines
Fraud vendors cannot be left on autopilot either. A vendor that assumes chargeback liability may become more conservative when order values rise, while a non-guaranteed vendor may be more willing to approve risky transactions.
Neither model is automatically right or wrong.
The important thing is staying involved in the fraud strategy, understanding how the vendor responds to volatility, and making sure the approval approach supports payment fraud prevention, marketplace fraud prevention, and healthy growth.
That is where fraud risk management becomes practical. It is not just about stopping loss. It is about balancing marketplace fraud, false declines, customer experience, and revenue in real time.
Strong playbooks and cross-functional trust protect the marketplace
Fraud teams cannot predict every sports result, viral product, celebrity event, shortage, or limited release. But they can prepare a reusable response playbook before the next market volatility fraud event happens.
That playbook should define:
What triggers an escalation
Who owns the response
Which fraud metrics matter
When vendors and leadership are contacted
How buyer and seller complaints are handled
When rules, models, or policies may need to change
How customer support, product, marketing, finance, and security participate
This is also why Mark recommends building a trust center of excellence. Marketplace fraud does not belong to one department. A seller fulfillment failure affects customer support. A promotion affects marketing and finance. A fake seller affects identity, payments, support, and legal. A chargeback spike affects fraud operations and executive leadership.
Fraud leaders are most effective when they act as strategic guides instead of automatic roadblocks.
The goal is not to say no to growth. It is to explain:
What risk the decision creates
What controls can reduce that risk
What data should be monitored
What thresholds should trigger action
How policy enforcement should work
How promotion abuse, refund abuse, and return abuse will be managed
That is how fraud operations, fraud strategy, and fraud risk management support the business instead of operating separately from it.
Fraud leaders need data, credibility, and time to recharge
Fraud professionals usually have great stories because they see sophisticated and sometimes unbelievable behavior every day. But one dramatic example is not enough to change a product roadmap or secure more resources.
The strongest fraud story combines:
A clear example
The number of similar incidents
The financial impact
The operational burden
The customer impact
The expected value of fixing it
Without data, leadership may treat the issue as a one-off. Without a clear story, the numbers may not feel urgent or memorable.
Fraud leaders need both.
That combination helps teams improve marketplace fraud detection, strengthen seller identity verification, justify payment fraud prevention resources, reduce false declines, and prioritize the right work across online marketplace fraud and resale marketplace fraud programs.
They also need to protect their own ability to make good decisions. Fraud rings do not wait for office hours, and high-severity incidents can pull teams into nights, weekends, and holidays.
That constant exposure can create exhaustion and make fraud professionals more likely to assume bad intent everywhere, including from their own coworkers.
Strong marketplace fraud prevention depends on experienced people who can think clearly, collaborate well, and make balanced decisions. Exhausted teams cannot sustain that forever.
Final takeaway
Marketplace fraud prevention is not just about catching stolen cards or blocking fake accounts.
It requires understanding how buyers, sellers, pricing, identity, fulfillment, chargebacks, policies, promotions, vendors, and real-world events interact. Market volatility can change those relationships overnight.
The marketplaces that protect trust best are the ones with strong fraud intelligence, flexible fraud monitoring, clear buyer and seller policies, reliable seller identity verification, effective KYS controls, prepared playbooks, and fraud leaders who understand how marketplace fraud, payment fraud prevention, chargeback prevention, fraud analytics, fraud risk scoring, and false declines all connect.
Because trust in a marketplace is earned in drops and lost in buckets. And once it is gone, it is very hard to get back.
Episode resources & links:
Connect with Mark Porteous | LinkedIn
Senior Director of Safety & Trust
Connect with Karisse Hendrick | LinkedIn
Host of the Fraudology Podcast
Award-Winning Cyberfraud Expert
Ecommerce Fraud Prevention Consultant
Startup Advisor, Keynote Speaker, and
Consultant to Fortune 500 merchants