Kalshi volume plunges 49.5% as light sports calendar exposes Robinhood-dependent model
Kalshi's notional volume fell 49.5% week-over-week to $2.09 billion for the week beginning May 11, its sharpest single-week decline in the dataset, after hitting a record $4.13 billion the prior week. The drop coincided with a light sports calendar, which has become the dominant driver of Kalshi trading activity. Robinhood accounts for more than half of Kalshi's total notional volume, reflecting the brokerage's growing role as a distribution channel. Transaction count fell 46.4% to 13.0 million, pointing to larger average trade sizes rather than broad activity pullback. Polymarket global held comparatively steady, dipping just 1.7% to $1.58 billion, its most resilient week relative to Kalshi in over a month. Polymarket's US version reversed its prior-week collapse.
Robinhood's majority share of Kalshi volume means the brokerage's trading rhythms now dictate the exchange's weekly prints. Any sustained slump tests whether Kalshi can maintain its license-expansion narrative when half its flow rides a single partner's retail calendar.