Public Prediction Markets

What it is

Public Prediction Markets is an event-contract hub inside Public, the US brokerage app for stocks, options, bonds and crypto. A reader opens an event, picks Yes or No on an outcome, and enters either a number of contracts or a dollar amount, which Public converts into whole contracts. Contracts also show up on the asset pages of related stocks, and the positions sit in the same portfolio as everything else.

Three parties sit behind the button:

• Open to the Public Investing, Inc., the broker you deal with: a FINRA and SIPC member broker-dealer for securities and, for event contracts, a CFTC-registered futures commission merchant and NFA member (NFA ID 0465334, per its own risk disclosure dated 20 August 2026).
• Apex Clearing Corporation, the clearing FCM. Public's Event Contracts Customer Agreement says Public Investing routes each order to Apex Clearing, Apex routes it to KalshiEx, and Apex clears it through Kalshi Klear.
• KalshiEX LLC, the exchange, named in the footer of every prediction-markets page: "Event contracts offered by Open to the Public Investing, Inc. and Apex Clearing Corp. through KalshiEX LLC."

Public is one more broker layer above Kalshi, with the same book underneath. What it adds is the brokerage around it: the same account and buying power as the reader's stocks, an API, an MCP server and rule-based AI agents that can use a contract's price to trigger a trade in something else.

Availability

US residents with a standard Public account. The product page says prediction markets are open to anyone eligible for a Public brokerage account: at least 18, a Social Security number, a permanent US residential address, and US citizenship, a green card or a valid US visa. The Event Contracts Customer Agreement adds the representation that you are a resident of the United States, and lets Public ask for or re-verify identity documents when the event contracts account is opened, even for an existing customer.

Enabling the product is an onboarding flow in the app: a short introduction, questions about trading experience, a profile review and the terms. An affiliation with a commodities firm or a regulator, or an open investigation, sends the application to manual review. A reader whose answers suggest the product is too risky is shown an extra Heightened Risk Disclosure under NFA Rule 2-30 before completing the application.

No state list is published. Nothing Public has published names a state that cannot trade. The customer agreement reserves the right to restrict the account and cancel pending orders wherever Public "has made a risk-based decision to restrict access", as well as in sanctioned jurisdictions. The state rulings against Kalshi that its card records concern sports contracts, which Public does not list, and its risk disclosure says a court ruling against such contracts could force liquidations through the exchange. Read 2026-10-23.

Pricing

No subscription, two cents a contract per trade. Public's fee schedule, last updated 13 October 2026, lists event contracts in their own section: a transaction fee of "$0.01 per contract", charged by Public Investing as the FCM, and "an exchange fee of $0.01 per contract, which is charged by the exchange and passed on to the customer". A footnote says the exchange fee is set by KalshiEx LLC and can change without notice. The help centre puts it as "a 2-cent fee per contract traded on Public, one cent for an exchange fee and one cent for a commission fee", and the order screen shows the fee before you submit.

So both fee fields read 2: two cents on a $1 payout, at any price, whether the order rested or took. Holding to settlement pays it once, and selling first pays it again. The flat fee is why Public blocks buy orders at 99 cents: with the fee, the contract would cost $1.01 and pay at most $1.

Public's exchange-fee line does not match Kalshi's published formula. Kalshi's own schedule charges takers a curve, 0.07 × price × (1 − price) per contract rounded up, which is 1.75 cents at 50 cents and less towards the edges, and charges no maker fee on most series. Public prints the exchange fee as a flat cent "set by KalshiEx". Neither Public's schedule nor its help centre says how the two relate, and this card does not guess. It records what Public's schedule says a Public customer pays. Against a direct Kalshi account that comes to 0.25 cents more for a taker at 50 cents, more again at the extremes, and 2 cents more for a resting order.

Access to the API is free; trades placed through it, the MCP server or an agent pay the same two cents. Public's account-wide charges (wire, paper statement, inactivity) are on the same schedule and are not specific to event contracts.

Markets & resolution

Markets that move markets, and no sports. The help centre says Public focuses on events and contracts that can move financial markets and does not list sports. The hub's categories on 23 October 2026 were climate and weather, commodities, companies, crypto, economics, elections, financials, health, industries, markets, politics, science and technology, and transportation. The product page names Fed decisions, CPI, GDP and unemployment, company results and delivery targets, court rulings and FDA approvals, elections and confirmations, and crypto, oil and metal price levels. Public takes requests for new contracts but promises none.

Public resolves nothing. Each event page prints the outcome rules, the source (the Federal Reserve for a rate decision), the estimated resolution date and a link to the full contract terms, and those are Kalshi's. The risk disclosure says the Yes and No sides are separate contracts with Kalshi Klear as the original counterparty, that positions cannot be moved to another exchange, and that payout follows the reported source. A closed event can still be waiting for resolution; payout lands in the account once the outcome is confirmed.

Trading runs around the clock, apart from a maintenance window every Thursday from 3:00 to 5:00 am ET. Orders are limit (the default; day or good-till-cancelled) or market. Public may restrict a thin, wide or low-open-interest contract to limit orders only, and the customer agreement lets it cap the number or size of positions at its discretion. Positions cannot be moved to another broker in an account transfer.

Integrations

• Public API and Python SDK. The API reference has an Event Contracts section (event summary, categories and details), and the help centre says prediction-market trading works through the API with the same contracts as the app. The product page invites readers to code their own strategies against it. No streaming endpoint is documented for event contracts.
• Public MCP server, hosted, for connecting the account to Claude, ChatGPT and other assistants, covering prediction markets with the same permissions as the app.
• AI Agents. You describe a rule in plain English, such as alerting you when a rate-cut probability rises ten points in a day or buying contracts when a price crosses a level. Public's AI turns it into a workflow, which you review and approve before it runs. The product page also describes an AI market briefing on what moved in prediction markets.

This card sets charting for the price history on each event page (one day to all time) and tax_reporting because Public's help centre says it issues a Form 1099-MISC for event contract transactions.

Limitations

• Only for Public customers in the US. Event contracts are an add-on to a Public brokerage account, enabled through onboarding.
• A flat 2 cents a contract each way, which is a fifth of the price of a 10-cent contract.
• The exchange fee Public prints is not Kalshi's published formula, and Public does not say why.
• No sports, by policy, and no published state list.
• AI on the account. ai_features reads research for the AI briefing and for agents that can research markets and walk through a potential trade on request. Public's disclosures say agents act only on the reader's own instructions, after the reader confirms each one, and that their output is not a recommendation. The Agentic Brokerage disclosure names execution through Public Investing and Zero Hash only and does not mention event contracts, although the help centre says agents trade them.
• No SIPC cover. Public's own disclosures say event contract accounts are not SIPC protected.
• Mobile flow. The help centre describes placing a trade by tapping in the app. The website shows prices and contract terms, and this card does not claim trading on the web.
• Nobody here has funded an account. Everything above is read from Public's prediction markets pages, help centre, fee schedule, Event Contracts Customer Agreement, risk disclosures, Agentic Brokerage disclosure and API documentation, on 23 October 2026.

Alternatives

Kalshi direct has the same book, its own fee curve and the full market list, sports included. tastytrade is the other brokerage on Apex's clearing route into Kalshi, at the same two cents a contract with a narrower macro-only list. Webull and Robinhood are the brokerage apps with sports; the Kalshi-through-a-broker head-to-head sets their fee layers side by side.