Every market has its legends, and prediction markets minted theirs in November 2024. The stories below are not just trivia: each one shows something real about how these markets work — how information gets priced, what a single trader can and cannot move, and why the incentives to be right are the whole point. Figures are drawn from Wall Street Journal, CBS and blockchain-analysis reporting.
The French whale’s $85 million
The largest known win in prediction-market history belongs to an anonymous French trader known as “Théo”. In October 2024 he began building an enormous position on Donald Trump winning the presidential election on Polymarket — first around $30 million, eventually roughly $80 million staked across as many as 11 accounts (one, “Fredi9999”, became famous in its own right). He told the Wall Street Journal he had sold virtually all his liquid assets to fund it, that he had no political agenda, and that he was “just making money.” When Trump won, blockchain-analysis firm Chainalysis put his total profit at more than $85 million — the single largest election bet, and payout, ever recorded.
How he found the edge
What elevates the trade from gamble to legend is the homework. Convinced that conventional polls under-counted “shy” Trump voters, Théo commissioned his own surveys from YouGov using neighbour polling — asking swing-state respondents in Pennsylvania, Michigan and Wisconsin not just who they would vote for, but who they thought their neighbours would vote for, a technique from academic literature designed to surface preferences people will not admit to a pollster. The results showed the hidden Trump support he suspected, and he sized up accordingly. It was not riskless: the day before the election his known accounts sat on roughly $3 million of unrealised losses, and his position was so large — about a quarter of all “Trump wins the Electoral College” contracts — that he could not have exited without crashing the price. Conviction, private information, and the nerve to hold: that was the trade.
The market that traded billions
The stage itself was historic. Polymarket’s 2024 presidential-winner market alone cleared well over $2 billion in volume, with total election-related trading on the platform reported above $3 billion — while Kalshi, Robinhood and Interactive Brokers ran regulated US election markets for the first time in a century after Kalshi’s court victory. The markets also called the race well: they moved toward Trump ahead of most forecasters and settled cleanly — the episode that, more than any other, pushed prediction markets into the mainstream and set up the explosive growth of 2025–26.
What traders can actually learn
Copy the process, not the size. The whale’s edge was original research the market had not priced — the same principle behind every good trade at any scale, as our strategy guides argue. His discipline in sizing to conviction (and accepting he could be wrong) is textbook bankroll thinking — though staking most of your liquid net worth on one outcome is exactly what those guides tell you never to do. And the episode is a live case study in the manipulation debate: many assumed the whale was propping Trump’s price to shape sentiment, when the money was simply better informed than the polls. Sometimes the market is not being manipulated — it is being right early.
More on how we got here
This page is part of our series on the story and scale of prediction markets:
Frequently asked questions
What is the biggest prediction market win ever?
The French trader known as “Théo” made more than $85 million on Polymarket betting roughly $80 million that Donald Trump would win the 2024 US election, per blockchain-analysis firm Chainalysis — the largest known election bet and payout in history.
How did the French whale know Trump would win?
He commissioned private YouGov polls in Pennsylvania, Michigan and Wisconsin using “neighbour polling” — asking people who they thought their neighbours would vote for — a technique that surfaced shy Trump support the public polls were missing.
Did the whale manipulate the market?
The evidence says no. He told the Wall Street Journal he had no political agenda and was simply trading his research; his position was so large he could not have exited without crashing the price, and the outcome vindicated his numbers.