# Susquehanna International Group A quantitative trading and market-making firm founded in 1987 by six friends from SUNY Binghamton — [[Jeff Yass]] among them — who had learned probability at the poker table and applied it to options. Privately held, headquartered in Bala Cynwyd outside Philadelphia, SIG is one of the largest options market-makers in the world and trades in nearly everything else, training its people through an in-house poker program and a proprietary curriculum. It is in the vault for two reasons: it is the source of Yass's fortune and therefore of one of the largest streams of Republican and libertarian money in the country, and its venture arm made the single most consequential early bet in American media politics. ## The ByteDance stake In 2012 SIG's Asian venture arm put a few million dollars into a Beijing startup called ByteDance. The firm now holds about 15% of TikTok's parent — Yass personally about 7%, worth an estimated $21 billion — which made SIG the largest outside shareholder in a company whose American future became a matter of statute. The [[TikTok Ban (2020-2025)]] page has the sequence: the 2024 divest-or-ban law, the January 2025 reprieve, and the year of extensions that followed. Yass's money and access — he met Trump in March 2025, and the President's reversal from banning TikTok to saving it followed his conversations with Yass and others — are the reason the case sits in the [[Foreign Influence Ecosystem]] file as well as the media one. When the U.S. joint venture closed on **January 23, 2026** (Oracle, Silver Lake and MGX at 15% each, ByteDance at 19.9%, the rest with existing investors), SIG's affiliate Vastmere Strategic Investments took a stake and a board seat, held by Mark Dooley, one of the firm's first employees. The investor who funded the app is now among the owners of its American successor, with the government's blessing. ## The money Yass is the firm's political face and, in most cycles, the largest individual donor in Pennsylvania and one of the largest in the country: about $100 million to Republican candidates in 2024, $16 million to MAGA Inc. and at least $2.5 million to the White House ballroom in 2025, and tens of millions each cycle for school choice — the cause he cares about most — through the [[Commonwealth Leaders Fund]] and the Club for Growth network. SIG's other founders give less and differently. The firm itself is the pattern the [[Campaign Finance Timeline]] tracks: a private partnership with no shareholders to answer to, whose trading profits become political money with no disclosure between the two. [[Jeff Yass]] has the giving; [[Palmer Luckey News Log]] and the defense-tech pages have the other quant-fortune donors it is usually grouped with. ## See Also - [[Jeff Yass]] · [[Commonwealth Leaders Fund]] · [[Campaign Finance Timeline]] - [[TikTok Ban (2020-2025)]] · [[TikTok]] · [[ByteDance]] · [[Foreign Influence Ecosystem]]