Polymarket vs. Kalshi: which looks more overvalued?

As of 1 October 2026. Verdict: Polymarket looks more richly valued relative to its current trading activity and reported revenue. Confidence: moderate to low. This is a relative judgment about two private companies, not a finding that either company's shares are worth less than a particular price. The strongest comparison uses the funding valuations currently being discussed—about $21 billion for Polymarket and $40 billion for Kalshi—but neither entire round has been publicly confirmed as closed. Bloomberg reported Polymarket's planned round; Reuters reported Kalshi's still ongoing talks on 29 September.

What is known, and what is only reported

Measure	Polymarket	Kalshi	Evidence status
Latest transaction with a public, usable price	In March 2026, ICE paid $600 million for about 4.2 million Series E preferred shares. Its roughly $2.0 billion combined preferred stake was 14% of Polymarket on a fully diluted basis. Those rounded figures imply about $14 billion for the fully diluted equity at the Series E price; Polymarket itself did not announce that valuation.	Kalshi announced a $22 billion valuation in its May 2026 $1 billion Series F round.	ICE SEC filing; Kalshi announcement. The Polymarket figure is my inference from a preferred share transaction, not a confirmed common share value.
Newer funding price under discussion	$21 billion post-money for a planned $1 billion round led by 1789 Capital, reported 31 August.	About $40 billion in talks for roughly $1 billion of fresh capital, reported 29 September and expected to close later.	Bloomberg; Reuters. These are reported prospective terms, not comparable completed rounds.
July 2026 global notional taker volume	$12.89 billion across Polymarket International and US.	$40.10 billion.	My sums of the four topic columns for each venue in Pew Research Center's published table. Pew's underlying data came from The Block.
Recent annualized revenue	Reuters reported that a source said the run rate exceeded $1 billion in June; Sacra estimates roughly $1 billion then.	The Information reported more than $4 billion annualized in July, citing a person familiar with the matter; Sacra estimates roughly $4 billion.	Unaudited estimates or source claims, observed in different months. Annualizing a strong month does not establish full-year revenue or profit.

Kalshi's August Form D reports $1.12 billion of equity sold in an offering that began in April, but it states no share price or valuation. It therefore cannot verify the proposed $40 billion price or prove that the later round is complete. A private-market listing labels a 17 September financing a $40 billion Series G, while Reuters reported on 29 September that a $40 billion round was still in talks; without disclosed transaction terms, I treat the price as unverified. ICE likewise said it would disclose the valuation of its March Polymarket investment after the fundraising was completed. ICE had previously described its October 2025 commitment as valuing Polymarket at approximately $8 billion before investment; treating that as a current $8 billion valuation would ignore the later transaction.

Why the relative call favors Kalshi

Inference from matched activity. In Pew's July data, Kalshi traded 3.1 times Polymarket's notional volume, while its proposed valuation is 1.9 times Polymarket's ($40 billion versus $21 billion). The implied valuation per dollar of that month's notional volume is about $1.00 for Kalshi versus $1.63 for Polymarket. This ratio is a rough scale check, not a price-to-sales multiple: Pew counts each taker contract at its $1 payout value, not the trade price or the fee retained by the platform. Pew's methodology and venue data.

Inference from reported revenue. Using Sacra's estimates of about $1 billion for Polymarket and $4 billion for Kalshi, the proposed prices imply roughly 21 times versus 10 times annualized revenue. Even using the last observable transaction prices (about $14 billion inferred for Polymarket, $22 billion announced by Kalshi) yields roughly 14 times versus 5.5 times those later run rates. These are illustrations, not defensible enterprise-value multiples: the revenue estimates are neither audited nor from the same month, and the valuations and run rates occurred at different dates. Sacra on Polymarket; Sacra on Kalshi; ICE filing; Kalshi announcement.

Polymarket has value that these ratios do not capture: it has an international market, a stronger politics niche in Pew's data, and an ICE agreement to distribute its event data. In July, Polymarket's US venue was already 39% of its combined volume, and politics volume on Polymarket had averaged about $2 billion monthly in 2026, versus less than $300 million on Kalshi, according to Pew. It is unknown how much incremental profit the data deal or political market position will produce. Some Polymarket markets, including geopolitics, remain fee-free, so headline volume cannot simply be turned into revenue.

Risks and conditions that could reverse the verdict

Both companies' recent growth relies heavily on sports. In July, sports accounted for about 78% of Kalshi's and 82% of Polymarket's notional volume in Pew's table. Both US exchanges appear on the CFTC's designated contract market list, yet New York has sued Kalshi and Polymarket US, alleging illegal unlicensed gambling. Those are allegations, not court findings. A restriction on sports contracts could particularly damage the revenue run rates used here; the outcome is unknown.

At the proposed $21 billion/$40 billion valuations, Polymarket would need annualized revenue of at least 52.5% of Kalshi's to match Kalshi's simple valuation/revenue ratio. If Kalshi sustainably earns $4 billion annually, that threshold is $2.1 billion for Polymarket. Conversely, if Polymarket's sustainable revenue is only $1 billion, Kalshi's would have to fall below roughly $1.9 billion for Kalshi to become the more expensive of the two on this measure. Both thresholds are my arithmetic, not forecasts. They show why a World Cup month, fee definitions, and future monetization matter.

Unanswered questions: What were each company's actual trailing-12-month net revenues, fee rebates, customer acquisition costs, cash burn, and operating profit? Have either of the proposed rounds closed at the reported price, and what are the new-round preferred-share rights and fully diluted share counts? How much of July's sports volume and fees persist through ordinary months, and how will the state litigation affect access? Without those answers, the report supports Polymarket as the more stretched relative price, but cannot establish a precise fair value for either company.