Jeromee “JJ” Johnson has spent a large part of his career preparing financial systems for conditions their designers cannot predict. The importance of that work became clear on May 6, 2010, when U.S. stocks plunged and rebounded within minutes, with some securities trading at prices no rational buyer or seller would recognize.
The Flash Crash revealed how quickly trouble could spread through a market linked by automated trading strategies, competing exchanges and rules that did not always produce a coordinated response.
Johnson was part of the executive team driving BATS Global Markets’ transformation from a single equity exchange into a major cross-asset operator. He built the BATS Options Exchange from inception and, after the Flash Crash, led the effort across U.S. exchanges to harmonize the rules for clearly erroneous trades and to modernize market-wide circuit breakers. The work forced exchanges, regulators and market participants to decide how an interconnected market should respond when its normal safeguards failed.
Johnson brought a mix of technical training and capital-markets experience to the assignment. He studied mathematics and physics at Yale University. At TABB Group, he advised capital-markets firms on technology and strategy while writing about low-latency market data and hard-to-find liquidity. He went on to co-found 3D Markets, the first U.S. equity options dark pool, before joining BATS. He later ran global markets at Miami International Holdings. Since 2018, he has also served on the board of Demand Derivatives Corp.
Today, Johnson serves as President and CTO of Tellus App, Inc., a fintech and proptech company founded in 2016 by Rocky Lee and T Zhu. Its platform serves both savers and property owners. Savers set goals, take quizzes and build streaks, and they earn rewards by claiming Boosts or completing tasks tied to them. Landlords use Tellus’s free property management software to collect rent, handle maintenance requests and manage daily operations. Tellus is not a bank. Tellus is not FDIC-insured.
Distinct from its consumer products, Tellus operates a separate real estate lending business that makes business-purpose loans on non-owner-occupied residential properties with one to four units. It works through licensed mortgage brokers, its loans are secured by liens, and it does not make consumer loans.
Johnson now works in a different corner of finance, but reliability remains central: software must be accurate, easy to understand and able to hold up when users do something its designers never anticipated.
“Capital markets teach you that technology is never just the code,” Johnson explained. “It is the code, the rules, the incentives, the operating procedures and the way people respond when conditions change. If you design only for the expected path, the system will eventually show you everything you failed to consider.”
Johnson sees reliability as a starting point, not a final check before launch. It shapes the earliest design decisions and is tested again once the product reaches the people who will use it.
His exchange work holds three lessons for fintech: how systems behave where they connect, how to scale reliably, and how to make complex technology work for the people who use it.
Reliable Systems Are Only as Strong as the Connections Between Them
The Flash Crash showed how individual technologies can perform as programmed while the market as a whole produces an unacceptable result. A pause on one exchange offers little protection if trading simply moves elsewhere. Confidence suffers, too, when the standards for reversing erroneous trades are unclear.
Preventing another breakdown required a coordinated response. For Johnson, the hardest part was getting competing exchanges to agree on shared rules. The Securities and Exchange Commission approved pauses in individual stocks across U.S. equity markets when price changes reached defined thresholds. Exchanges and the Financial Industry Regulatory Authority also adopted clearer standards for determining when erroneous trades should be reversed.
Johnson sees a parallel for fintech companies. A polished interface can conceal weak connections among vendors, data providers, payment networks and internal systems. The practical questions are which system holds the official record, how customers can recover from an interruption and who steps in when automation cannot resolve a problem.
Johnson’s operating discipline is to focus on structural problems instead of chasing symptoms: a quick fix may stop the immediate problem without correcting the breakdown that allowed it to spread. Reliability depends on how the entire system performs, not on whether one component can claim perfect uptime.
Scale Exposes Every Decision a Team Has Left Informal
BATS grew to nearly a dozen exchanges during Johnson’s tenure. Each expansion added another layer of operating complexity. New rule sets, market participants and data flows had to integrate with infrastructure already running at speed.
Building an exchange from the ground up taught Johnson to look well beyond matching and executing orders. The venue needed controls to manage risk, meet regulatory obligations, support market makers, resolve trade errors and keep operating under stress. Those capabilities had to scale with the business because adding them after the fact was not a viable option.
Johnson sees the same pressures building more quietly inside growing fintech companies. Early teams often rely on a few employees who carry critical knowledge in their heads. The model works until transaction volume rises, the number of vendors increases or the person with the answer is unavailable.
Operational maturity begins when a company turns institutional knowledge into repeatable processes. Decision rights become explicit. Monitoring moves beyond uptime to business outcomes. Escalation paths are established before an incident, and small deviations are investigated before they develop into costly failures.
He describes the principle this way: “Design for where you need to be at full maturity, even while you’re executing at today’s stage.”
A startup does not need to replicate the bureaucracy of a mature financial institution. Essential controls, however, need to develop ahead of volume, complexity and regulatory scrutiny, not in response to them.
Reliable Financial Technology Gives People Clarity Without Taking Away Control
Exchange systems may be complex, but their purpose is clear. Market participants need to operate under shared rules and understand how their trades were handled. Consumer financial technology carries a similar responsibility, because people rely on it to make decisions about their money and property.
Convenience should make those decisions easier, not take them away from the user. Savers set their own goals and choose whether to act. Landlords decide how to manage their properties while software helps organize administrative work. Technology can organize information and reduce friction, but judgment stays with the saver or the property owner.
The way people use a product also tells development teams where it is falling short. An abandoned step may signal unnecessary friction. A repeated question may expose an unclear instruction. A workaround may reveal that the product does not match how customers behave.
“The market itself tells you the truth faster than any report does,” Johnson says.
Johnson has brought the discipline of an exchange operator to his work at Tellus. That means asking whether systems can handle unusual conditions, whether responsibilities are clear before a problem occurs and whether a failure in one component could affect the rest. It also means asking whether customers can understand what is happening well enough to decide what to do next.
Johnson still takes part in market-structure debates. In an April 2026 public comment to the Commodity Futures Trading Commission on prediction markets, he urged the agency to bring back the economic purpose test for event contracts. “The economic purpose test existed for a reason,” he wrote. “That reason has not gone away.” In a June 2026 ProMarket essay, he applied lessons from trading venues to online loan marketplaces, where shopping around can earn borrowers worse terms.
Johnson also mentors CEOs and small business owners through the Helzberg Entrepreneurial Mentoring Program, a Kansas City-area initiative that pairs experienced entrepreneurs with developing business leaders for one-on-one guidance and peer mentoring.
In his work at Tellus and with the entrepreneurs he mentors, Johnson returns to the same principle: a small technical or operating decision can quickly affect an entire system. Technology earns trust when it performs outside ideal conditions, tells users what is happening and remains useful when things do not go according to plan.
Tellus is not a bank. Tellus is not FDIC-insured.
