Fintech founder; former MayStreet CEO; energy-tech founder · MayStreet (co-founder/CEO; acquired by LSEG); Ground Floor Energy (founder) · Waukesha, Wisconsin
Patrick Flannery
MayStreet co-founder and former CEO (market-data / low-latency trading tech), later LSEG head of low latency and direct feeds, now Ground Floor Energy founder. Not Patrick S. Flannery (ex-AMSC Pewaukee / UW–Madison ECE). Not Kentucky Rep. Patrick Flannery.
Net worth
$20 million+
September 3, 2026
About
Patrick Flannery built MayStreet into a specialist market-data and low-latency trading-technology firm that banks, hedge funds, and regulators came to rely on.
He co-founded the New York company in 2012 with Michael Lehr after engineering roles at proprietary shops including Volant Trading and Sumo Capital, expanding from feed-handler libraries into pristine packet-capture historical data.
London Stock Exchange Group agreed to buy MayStreet in 2022. Flannery stayed on as global head of LSEG's low-latency and direct-feed business, then launched Ground Floor Energy, a climate-tech and project-finance venture combining batteries, renewables, and software. He studied computer science at the University of Colorado Boulder and long worked from the greater New York markets orbit.
Waukesha is the Wisconsin city on his page. Public professional footprints put him in New York markets and later London rather than a published Waukesha residence.
Companies and affiliations
- MayStreet (co-founder/CEO
- LSEG)
- Ground Floor Energy (founder)
Notable facts
Co-founded MayStreet in 2012 with Michael Lehr; served as CEO until the LSEG acquisition.
LSEG announced agreement to acquire MayStreet in May 2022; MayStreet had supplied data to the SEC MIDAS system since 2019 and served more than 65 institutional clients.
After the deal, described publicly as global head of LSEG's low-latency and direct-feed business; prior roles include Director of Engineering at Sumo Capital and Senior Engineer at Volant Trading.
Founded Ground Floor Energy (climate and energy project finance); press has described the startup as New York–based.
Delaware Chancery coverage has tracked post-acquisition litigation between Flannery and LSEG over earnout and integration disputes (2025–2026).
What questions can this profile answer
- What makes Patrick Flannery notable?
- Patrick Flannery built MayStreet into a specialist market-data and low-latency trading-technology firm that banks, hedge funds, and regulators came to rely on. He co-founded the New York company in 2012 with Michael Lehr after engineering roles at proprietary shops including Volant Trading and Sumo Capital, expanding…
- What is Patrick Flannery's estimated net worth?
- Patrick Flannery's estimated net worth is $20 million+ as of 2026-09-03.