15-minute Bitcoin markets supply 95% of Kalshi’s September crypto growth

Kalshi’s 15-minute Bitcoin contracts accounted for 95.3% of the exchange’s net increase in crypto notional volume from August to September 2026, delivering virtually all of the category’s monthly growth. Kalshi’s crypto notional volume rose 17.2%, from $7.58bn in August to $8.89bn in September, driven primarily by the 15-minute Bitcoin series, which increased 22.6% to $6.75bn.

15-minute Bitcoin markets supply 95% of crypto growth

Kalshi’s 15-minute Bitcoin series added $1.245bn month-on-month, almost the entirety of the crypto category’s $1.306bn net increase between August and September 2026. The nine short-duration 15-minute contracts (Bitcoin plus eight other assets) produced $7.63bn in September, up 22.5% from $6.23bn in August. Those contracts’ combined share of Kalshi’s crypto volume rose from 82.1% in August to 85.8% in September.

All other Bitcoin formats declined about 6.1%, falling from $1.26bn to $1.18bn. Within those longer formats, contracts settling on whether Bitcoin would finish above specified price thresholds fell 6.5%, from $1.22bn to $1.14bn. Activity concentrated in the latter half of September: Bitcoin’s 15-minute series produced $3.74bn during Sept. 16–30, up 24.4% from $3.01bn during Sept. 1–15. Across all crypto formats on Kalshi, volume increased 21.4% between those two equal 15-day periods.

"Fifteen-minute Bitcoin contracts represented 75.9% of September crypto volume, up from 72.6% in August," the TickerTracker data show, underscoring the format’s growing dominance.

15-minute markets across altcoins showed mixed results

Trading in cryptocurrencies other than Bitcoin rose roughly 16.9% across all durations. Among altcoin 15-minute products, Ethereum, XRP and Solana recorded volume gains, while HYPE and BNB declined. Volume in Zcash and NEAR more than doubled, reaching $47.4m and $37.4m respectively. Despite those increases, the format’s growth was not uniform across assets: the 15-minute format concentrated liquidity in the few largest series.

15-minute commodity markets: gold supplies two-thirds of the gain

Kalshi’s commodity notional volume jumped 117.3%, from $410.2m in August to $891.3m in September. Seven 15-minute commodity series generated $864.9m of September volume. Gold led with $541.6m, WTI crude oil followed at $137.8m and silver reached $105.4m. Gold and silver together made up 72.6% of the commodity category.

Kalshi launched 15-minute gold and silver markets in August; gold’s volume rose 149.5% in September, with a $324.5m increase that provided 67.5% of the category’s net growth. Gold’s share of commodity volume rose from 52.9% to 60.8%, concentrating commodity trading in the largest series.

Changes across other commodity formats and time slices

Other commodity formats outside the seven 15-minute series shrank 33.1%, from $39.5m in August to $26.4m in September. Hourly gold volume fell 75.2%, from $7.3m to $1.8m; hourly silver dropped 85.8% to roughly $517,000. Daily gold markets slid from $3.0m to $1.8m. Weekly natural gas was an exception, climbing from about $150,000 to $836,000, though it remained small next to the $29.5m traded in 15-minute natural gas contracts.

Copper and natural gas each saw stronger trading in September’s second half: their volumes rose roughly 41% between Sept. 16–30 and Sept. 1–15. Reported September totals for copper and natural gas were about 20x and 25x their August volumes respectively, partly because TickerTracker’s event records for those products begin on August 27. Average notional volume per reported event increased approximately 127% for copper and 181% for natural gas. Gold’s 15-minute volume rose 51.4% between the two halves, from $215.4m to $326.1m; total commodity volume increased 42.8% over the same periods.

Competitive supply: Polymarket US launches and Coinbase extends access

Polymarket US introduced 15-minute Bitcoin markets on September 22. During Sept. 22–30 those contracts produced $117.1m in notional volume. Over the same dates Kalshi’s 15-minute Bitcoin series generated $2.29bn, roughly 19.5 times Polymarket US’s initial nine-day volume. Polymarket US activity accelerated toward month-end: Sept. 28–30 contributed $71.4m, or 61.0% of its first nine-day total, while average daily volume rose from $7.6m during Sept. 22–27 to $23.8m in the final three days.

Despite scale differences, the format dominated both exchanges’ crypto categories: 15-minute Bitcoin contracts accounted for 89.5% of Polymarket US’s September crypto volume and 75.9% on Kalshi.

Coinbase highlighted its support for Kalshi-operated 15-minute crypto markets in an October 6 announcement, extending retail access to those short-duration contracts. The post positioned Coinbase as an additional distribution path to Kalshi’s products and shows how platform partnerships can broaden market access. For operators and market infrastructure vendors this combination of direct exchange liquidity and third-party distribution is a practical example of product reach and competitive dynamics. See the Coinbase announcement for vendor implications in broader distribution and access to Kalshi’s contracts: Coinbase announcement.

How notional volume is measured and why it matters

TickerTracker counts notional volume by assigning a $1 face value to each traded contract, regardless of the price paid; this measures trading activity and turnover rather than participant spending or revenue. The September figures therefore reflect contract-level activity and repeated turnover in 15-minute windows, not cash flow through the firms’ ledgers.

For product teams and market operators, the takeaway is clear: short-duration, high-frequency event contracts can concentrate activity rapidly in one or two dominant series, reshaping category composition within a single month.