Parlays Boost Kalshi; Polymarket Arrest, Fertitta, Sinner

Kalshi trading shows a large share tied to bundled sports bets known as parlays or “combos.” Analyst data indicate combos represent about 25% of the exchange’s volume. The same data estimate retail users’ returns on those prediction-market combos at roughly -18% return on investment versus about -12% ROI on comparable sportsbook parlays. Analyst Dustin Gouker wrote on social media, “25% is combos, which is almost entirely sports. 10% or so is crypto.” Kalshi has not excluded combos from its public breakdown of product mix.

Federal prosecutors charged Michele Spagnuolo, an Italian citizen and Google software engineer, with insider trading after officials allege she profited more than $1.2 million by placing bets on Polymarket markets tied to highly searched topics for 2025. Polymarket flagged suspicious activity linked to the accounts about six months before the charges, the company reported. Prosecutors allege the use of nonpublic information to place trades. Spagnuolo is the second person charged this spring in connection with suspected insider trading on event-based markets; an earlier case involved an accused U.S. service member who is alleged to have profited about $400,000.

In a corporate transaction, Tilman Fertitta won a bid to acquire Caesars Entertainment for $17.6 billion, a package that includes about $11.9 billion in assumed debt. Fertitta’s offer beat rival bidders and, subject to regulatory approvals, would take Caesars private. The buyer owns other gaming properties and has pursued control of Caesars for several years. The transaction’s financing and regulatory steps remain pending.

At the French Open, top seed Jannik Sinner lost in the second round to Argentina’s Juan Manuel Cerúndolo. Sinner led 6-3, 6-2, 5-1 before cramps and physical trouble produced a turnaround; he lost 18 of the final 20 games and was defeated in five sets. Sinner, who said he had not been feeling well and had “hit the wall,” was unable to complete the match after his physical condition deteriorated. Cerúndolo entered the match ranked outside the top 50.

Each story includes specific data and actions: trading volumes and ROI figures for Kalshi’s combos, criminal charges and company notifications in the Polymarket case, deal terms and outstanding approvals for the Caesars sale, and match scores plus postmatch comments for the French Open upset. Regulators and market operators have open oversight roles in the trading and corporate matters described above.