Polymarket’s combined monthly trading volume fell to $8.41 billion in August from $12.89 billion in July, a decline of about 35%, as the post-World Cup surge in prediction markets (platforms for trading event outcomes) faded. Kalshi’s volume slipped about 4% to $38.67 billion, leaving it processing close to five times Polymarket’s monthly volume. September weekly industry volume has continued at around $4 billion, below tournament-era levels. Investor interest remains strong: 1789 Capital, Donald Trump Jr.’s venture capital firm, led a $1 billion round valuing Polymarket at $21 billion, up from roughly $15 billion earlier this year. Polymarket reported more than 3 million users, while legal disputes involving both platforms continue.