Learn how IBKR founder Thomas Peterffy’s 2021 Kalshi acquisition offer, later partnerships, funding milestones, and regulatory battles shaped prediction market growth.
Interactive Brokers Founder Peterffy Made an Offer to Acquire Kalshi in 2021
Prediction market platformKalshico-founder andCEOTarek Mansour revealed in May 2026 that Thomas Peterffy, founder and chairman ofIBKR（Interactive Brokers）, had made an acquisition offer for Kalshi as early as 2021, but it was jointly rejected by Mansour and co-founder Luana Lopes Lara. The source was a LinkedIn post published by Mansour himself in May 2026.
The Acquisition Offer: Sequoia Partner Invited to Peterffy’s Private Residence
According to Mansour, Peterffy invited Sequoia Capital partner Alfred Lin to his private residence and presented an acquisition proposal for Kalshi in person. Lin was also a member of Kalshi’s board of directors, a role he took after Sequoia Capital led Kalshi’s USD 30 million Series A financing round in February 2021. Other investors in that round included Charles Schwab, founder of Charles Schwab, Henry Kravis, co-founder ofKKR, and SV Angel.
In the post, Mansour acknowledged Peterffy’s business foresight:
"At the time, Kalshi was still at a very early stage — very few users, very small trading volume, and almost no brand awareness. But Thomas saw its vision earlier than most people."
Although Peterffy was ahead of most investors in his industry judgment, Mansour and Lopes Lara still chose to reject the acquisition offer and keep the platform operating independently.
From a USD 30 Million Series A to a USD 22 Billion Valuation: Kalshi’s Funding Journey
Kalshi was founded in 2018 by Mansour and Lopes Lara, both graduates ofMIT. The platform was approved by the U.S. Commodity Futures Trading Commission（CFTC）as a designated contract market（DCM）in November 2020 and officially launched in July 2021. Over the following five years, Kalshi completed multiple large financing rounds:
| Funding Round | Announcement Date | Amount Raised | Post-Money Valuation |
|---|---|---|---|
| Series A | February 2021 | USD 30 million | Undisclosed |
| Series C | June 2025 | USD 185 million | USD 2 billion |
| Series D | October 2025 | USD 300 million | USD 5 billion |
| Series E | December 2025 | USD 1 billion | USD 11 billion |
| Series F | May 2026 | USD 1 billion | USD 22 billion |
The Series F round was led by Coatue Management, with participation from Sequoia Capital, Andreessen Horowitz, Paradigm, IVP, Morgan Stanley, and ARK Invest. According to Bloomberg, citing people familiar with the matter, Kalshi’s annualized revenue has reached USD 1.5 billion, with annualized trading volume of about USD 178 billion.
From Rejected Acquirer to Partner: The Changing Relationship Between IBKR and Kalshi
Five years after the acquisition was rejected, Interactive Brokers chose to enter prediction markets through partnership rather than acquisition. On May 14, 2026, IBKR announced the launch of a unified prediction market trading interface, integrating Kalshi,CMEGroup, and its own ForecastEx platform, allowing clients to compare prices across platforms and execute trades through a single account.
Kalshi CEO Mansour commented on the partnership as follows:
"IBKR is a benchmark in the global financial brokerage industry. Its integration with Kalshi proves the growing importance of prediction markets for sophisticated investors and financial institutions. Deep institutional participation in prediction markets is still in its early stages."
Peterffy himself also publicly expressed support for the informational value of prediction markets:
"Prediction markets are an important source of information for our clients. Our clients must understand economic development trends across different regions, consumer groups, and industries around the world."
Robinhood and Other Platforms Also Integrated Kalshi Event Contracts
In addition to Interactive Brokers, retail brokerage platforms such as Robinhood and FOREX.com under StoneX have also established partnerships with Kalshi to offer event contract products to their clients. Financial data services provider Tradeweb Markets has taken an institutional route, partnering with Kalshi through a strategic investment and minority equity stake, with plans to integrate event contract data into its rates and credit market infrastructure.
Current Legal and Regulatory Challenges Facing Kalshi
Kalshi’s rapid expansion has not come without resistance. Sports betting currently accounts for more than 90% of the platform’s trading activity and about 89% of its revenue, putting it in direct conflict with state gambling regulators.
As of May 2026, a total of 11 states had initiated legal proceedings against prediction market platforms. Arizona once filed criminal charges against Kalshi, alleging that it constituted an "illegal gambling operation".
Massachusetts sued Kalshi in September 2025, accusing it of circumventing sports betting regulations. In January 2026, Suffolk County Superior Court ruled that Kalshi’s sports event contracts were subject to the state’s gambling laws and issued a preliminary injunction.
The Nevada Gaming Control Board filed a lawsuit against KalshiEX in February 2026, seeking to prohibit it from offering unlicensed sports betting contracts within the state.
On February 19, 2026, a federal court in Tennessee ruled that Kalshi’s sports event contracts may constitute swaps and fall under exclusive federal jurisdiction, and accordingly issued a preliminary injunction in favor of Kalshi.
CFTC and Federal Government Support for Prediction Markets
In contrast to the hostile stance of some state governments, the current CFTC leadership clearly supports exclusive federal jurisdiction over prediction markets. On April 2, 2026, the CFTC, together with the U.S. Department of Justice, sued Arizona, Connecticut, and Illinois, alleging that cease-and-desist orders issued by the three states to prediction market operators violated the exclusive regulatory authority granted to the CFTC under the Commodity Exchange Act. CFTC Chairman Mike Selig warned that state intervention would threaten the operational stability of market participants and licensed entities.
The CFTC had previously voluntarily withdrawn its appeal in the Kalshi election contract case in May 2025, effectively giving Kalshi a green light to offer election-related event contracts. The case originated in September 2023, when the CFTC attempted to block Kalshi from listing election-related contracts. Kalshi sued the CFTC and won support from a federal district court in September 2024.
FAQs About the Kalshi Acquisition Event
What stage was Kalshi at when Thomas Peterffy tried to acquire it in 2021?
In 2021, Kalshi had just completed its USD 30 million Series A financing round led by Sequoia Capital and was about to officially launch operations. According to Mansour himself, the platform had very few users, extremely low trading volume, and almost no brand awareness at the time, but Peterffy had already judged its potential.
What role did Alfred Lin play in this acquisition offer?
Alfred Lin is a partner at Sequoia Capital and became a Kalshi board member after Sequoia led Kalshi’s Series A round. Peterffy invited Lin to his private residence and presented the acquisition offer in person, with Lin participating in the process as both a Kalshi board member and Sequoia representative.
How did Interactive Brokers establish a partnership with Kalshi after the acquisition was rejected?
Interactive Brokers launched a unified prediction market trading platform on May 14, 2026, integrating Kalshi, CME Group, and ForecastEx to provide clients with cross-platform price comparison and best net price execution. Kalshi is the core event contract provider in this partnership.
Why did Kalshi’s two co-founders reject Peterffy’s acquisition offer?
Mansour did not publicly disclose the specific reasons for the rejection. Based on subsequent developments, it can be inferred that the two founders chose to keep the platform operating independently and later raised Kalshi’s valuation from an undisclosed level through multiple financing rounds
