World Cup wagers helped double Kalshi’s revenue to a more than $4 billion annualized rate in July, from a pace of over $2 billion two months earlier, a person familiar with the matter said.

That growth is set to drive another jump in the prediction market’s valuation. Kalshi is in advanced talks to raise new funding at a $40 billion valuation, the person said, nearly double its valuation in a funding round announced in May. One potential wrinkle: Kalshi has been spending heavily to capture bettors’ attention and faces potential new expenses in the form of taxes in some of its biggest markets.