In September 2025, Thomas P. Gallagher’s exchange business acquired a distinctly human soundtrack. MIAX Sapphire began physical trading in Miami, adding brokers’ voices to a company associated with electronic markets. The room sat on the ninth floor of a Wynwood building, with skyline views and a very practical requirement: people needed to hear one another. Even the future of finance occasionally needs someone to check the acoustics.
Gallagher had spent years helping build the machinery behind financial transactions. Now there was a place where you could watch some of them happen. It makes a useful entrance to his story: a securities lawyer from Princeton, leading a business with Miami in its name, making room for people inside an enterprise built around computers.
His career has involved assembling the things a market requires before the first order arrives: capital, experienced colleagues, regulatory permissions and willing participants. The result became MIAX, the exchange group owned by Miami International Holdings. The interesting question is how a lawyer came to spend his working life building places where other people trade.
The lawyer on the other side of the transaction
Before MIAX, Gallagher was a founding partner of Gallagher, Briody & Butler, a corporate and securities law firm in Princeton, New Jersey. His professional world included public and private companies, debt and equity financing, and transactions across different industries. A law degree from Capital University Law School preceded a career spent helping companies work through the mechanics of raising money.
That background matters to the shape of the story. A securities lawyer works where ambition meets documentation. Someone has a business to build; someone else has capital; the transaction needs terms that both can accept. Gallagher’s later work brought those same constituencies into a different relationship, with an exchange company sitting between the people who wanted to buy and sell.
He became chairman of Miami International Holdings and the MIAX exchanges in 2008. The chief executive role followed in 2012. In December of that year, he joined the business full time, ending his association with the law firm. The first MIAX options exchange also launched in 2012. His change of occupation and the company’s arrival in the market shared a calendar.
It was a consequential move from advising businesses to assuming responsibility for one. He helped source capital and recruit experienced exchange professionals. Those tasks suited a founder whose contribution involved bringing people and financing together. An exchange could have excellent technology and still face an awkward opening-day question: who, exactly, intended to use it?
The people inside the machine
Gallagher’s explanation of the enterprise has consistently included the people who operate and use its systems. At a SALT panel in 2021, his account of the original idea included the words “invest in technology, invest in people and keep them together.” There is an unglamorous management problem inside that sentence. Recruiting an experienced team is one event. Keeping it working together is a continuing occupation.
On the same panel, he described member firms as shareholders and spoke about creating liquidity through technology and partnerships. The point was practical: a market needs participants willing to place orders and quote prices. Software gives them a venue. Their participation gives the venue something to exchange. The people outside the company become part of the operating equation.
There was a small personal aside, too. When moderator Jon Najarian mentioned his dual citizenship and Ireland, Gallagher said he shared that status. The conversation soon returned to trading infrastructure. It is a fleeting glimpse of a person in a discussion otherwise crowded with licenses, platforms and the vocabulary of financial plumbing.
By August 2025, Gallagher was still talking about the machinery. On MIAX’s first public trading day, he sat for an interview in a conference room with communications executive Andy Nybo and a white coffee mug nearby. “Technology is going to keep us here,” he said. A new stock ticker had arrived; his attention remained on the systems underneath the business.
“Technology is going to keep us here.”
Thomas P. Gallagher · August 2025
A ninth-floor answer
The Miami floor gives this otherwise abstract business a physical address and a set of design problems anyone can understand. MIAX Sapphire’s electronic exchange began trading in August 2024. Physical trading followed on September 12, 2025. The two belonged to the same exchange, giving market participants another way to execute options transactions.
The 38,400-square-foot facility occupies the ninth floor of 545 Wyn in Wynwood. It includes offices, conference facilities and a Bloomberg television studio. The design paid attention to lighting, sound and sight lines. Those details belong in the story because they describe what Gallagher’s company was actually building: a working environment whose users had to see, hear and interact effectively.
Douglas M. Schafer, MIAX’s chief information officer, described the floor as a project developed closely with member firms, with technology automating manual processes. Gallagher emphasized the expansion of access to the multi-listed options market. Each explanation comes back to the same test: whether the place helps participants conduct the business they came to do.
The setting also made the company’s name more tangible. Gallagher talked about Miami’s growing financial community, its business climate and its pool of industry professionals. The namesake city now had a trading floor. For a founder based professionally in Princeton, it was an expansion with both a commercial purpose and a pleasing geographical symmetry.
A wider map, a public company
Gallagher’s responsibilities had already spread beyond those two cities. He joined the Bermuda Stock Exchange Council in July 2019 and became its chairman in February 2020. In Minneapolis, he joined the MGEX board in October 2019 and became chairman in June 2021. That exchange is now called MIAX Futures. In June 2025, he added the chairmanship of The International Stock Exchange Group.
The map takes in different markets, different customers and different regulatory settings. During the 2021 panel, Gallagher explained the usefulness of having both securities and futures exchange permissions while the direction of digital-asset regulation remained unsettled. His legal background was visible in the reasoning: understand which activities the licenses allow, then consider what products can be built within them.
August 2025 supplied the public ceremony. Gallagher rang the New York Stock Exchange opening bell to mark MIAX’s initial public offering. The exchange operator had become a listed company itself. For someone whose earlier career involved helping businesses finance themselves, it was a particularly neat professional loop.
The offering closed on August 15, including the underwriters’ additional shares, with 17.25 million shares sold at $23 each. Gross proceeds were approximately $396.8 million. These are company financing figures, and they describe the resources raised for the business. The arithmetic belongs beside the bell: one marks the occasion, the other explains its financial scale.
Recognition followed in London on February 12, 2026, when FOW named Gallagher Chief Executive of the Year. His acceptance remarks included “success is never a solo effort,” and he dedicated the award to the MIAX team. The dedication echoed the people-and-technology argument he had made years earlier. The founder’s name was on the award; colleagues were in his explanation of how it happened.
What happens after the bell
By 2026, the next chapter was taking shape in futures. MIAX announced the launch of Tini Bloomberg 100 Index Futures in May, part of a suite based on Bloomberg equity benchmarks. Gallagher described the products as a way for retail and institutional participants to obtain and manage exposure to large American companies. Product development had moved into another concrete offering.
New contracts also need the arrangements that let customers use them. In September, MIAX announced that Dorman Trading, its futures commission merchant, had become a clearing member of the Options Clearing Corporation. Gallagher connected the membership to reducing operational burdens for customers trading the new financial futures. The business was working on the route into the market as well as the market itself.
MayBloomberg index futures begin launching.
SeptemberDorman gains OCC clearing membership.
The distinction is useful when considering Gallagher’s ambitions. Launching a product gives a company something to announce. Making it convenient for firms to trade that product requires further work, often involving institutions beyond the exchange. His public comments in 2026 put customer access alongside the continuing development of proprietary products and technology.
There is a pleasing continuity in that work. The lawyer who once helped companies arrange financing now leads a business arranging places, systems and permissions for transactions. The scale has changed. So has the responsibility. The need to bring several parties into a workable agreement remains familiar.
Back in Wynwood, the trading floor supplies the most legible picture of the whole undertaking. There are computers, and there are people who need a good view of one another. Gallagher’s career has brought him to both. A market opens at an appointed time. Building one occupies rather more of the day.