Yass vs Koch

Susquehanna International Group and Koch, Inc..

The differences

Forbes puts Julia Koch about $6.8B ahead of Jeff Yass.Forbes figures from 22 Sep 2026 and 16 Sep 2026.
Jeff Yass: co-founded it. Julia Koch: through marriage.

Put someone else on either side

Yass

Koch

Net worth, Forbes: $77.8BForbes, 16 Sep 2026; $84.6BForbes, 22 Sep 2026
Net worth, Bloomberg: $88.2BBloomberg, 10 Oct 2026; $78.5BBloomberg, 10 Oct 2026
Forbes rank: No. 30Real-Time list, 16 Aug 2026; No. 24Real-Time list, 22 Sep 2026
Billionaire since: 2021Forbes added him to the World's Billionaires list in April 2021 with $12 billion, after investigating his holdings; 2020Forbes named her the richest newcomer on its 2020 World's Billionaires list, at $38.2 billion, after David Koch died in 2019

How it started: Co-founded itCo-founded Susquehanna with a group of college friends in 1987; Through marriageShe and her three children inherited the 42% Koch stake of her husband David Koch, who died in 2019; they married in 1996
Main source: Susquehanna International Group, a proprietary trading firmBloomberg also credits him with a minority stake in ByteDance; The family's inherited stake in Koch, Inc.Koch says it has diversified from energy into consumer, technology, communications, healthcare and real estate
Companies: Susquehanna International GroupSusquehanna International Group: Co-founder and managing director; Koch, Inc.Koch, Inc.: Board member
Biggest stake: Susquehanna International Group51% owned; Koch, Inc.42% owned

Born: Year not statedNew York City, United States; 1963Iowa, United States
Country: United StatesLives in Haverford, Pennsylvania, United States; United StatesLives in New York City, United States
Education: Bachelor's degreeBS, State University of New York at Binghamton; Bachelor's degreeBachelor's degree, University of Central Arkansas
Parents: Son of two accountantsForbes adds that his father Gerald later helped build Susquehanna's back-office bookkeeping; Her family ran Flesher's, a used-furniture shop in Indianola, Iowa, where her father Frederic worked

Giving Pledge: Not a signer; Not a signer
Foundation: Yass Foundation for Education (Yass Prize)Janine and Jeff Yass founded the Yass Prize, run with the Center for Education Reform since 2021; Julia Koch Family FoundationFounded in 2023 with her children; she is also president of the David H. Koch Foundation
Lifetime giving: Not stated; $1.3BJulia Koch Family Foundation, 17 Oct 2026. 'More than $1.3 billion' given by David and Julia Koch together, through the David H. Koch Charitable Foundation and personal giving; a joint figure, not hers alone. Date is when the page was read

Role now: Runs the companyCo-founder and managing director of Susquehanna International Group; On the boardDirector of Koch, Inc.; chair of the Julia Koch Family Foundation and president of the David H. Koch Foundation
Successor: Not stated; No member of her family is named in a Koch executive role in the cited sources; Charles Koch is chairman and co-CEO with Dave RobertsonChase Koch is an executive vice president of Koch
Public office: None found; None found
Legal record: 1982: Philadelphia Stock ExchangeSettled an exchange disciplinary matter over a position-limit violation (Rule 1001) with a $1,000 fine, listed as disclosure 1 of 5 on his FINRA BrokerCheck report.; None found