How much one account may hold, and what happens past the line

Every regulated venue in this catalogue puts a number on how much of one outcome a single account may own, and almost none of them call the cap by the same name, measure it in the same unit or enforce it the same way. The two names that matter are position limit and position accountability level. They sound like synonyms. They are opposite ends of the same regulation.

How it works

One core principle, two tools

A designated contract market in the United States is bound by Core Principle 5, which 17 CFR 38.300 states in one sentence: to reduce the potential threat of market manipulation or congestion, the exchange "shall adopt for each contract ... as is necessary and appropriate, position limitations or position accountability for speculators." Where the Commission has set a federal limit for a contract, the exchange's own may not be higher. Section 38.301 adds that the exchange must meet parts 150 and 151 of the Commission's regulations, as applicable.

"Or" is the operative word. The regulation lets the exchange choose, contract by contract, and the two choices behave differently once you reach the number.

A position limit is a wall

Kalshi's rulebook, version 1.29, defines a Position Limit as "the maximum loss that can be incurred as a result of a position in a Contract that is allowed to be held or controlled by one Member or FCM Customer". Rule 5.19 makes it a violation to exceed one, and also to enter bids or offers "which would cause that Participant to exceed the applicable Position Limit" if accepted. A first violation may bring a warning letter or disciplinary proceedings; a second within twelve months of a warning brings proceedings. If you do not reduce as directed, the exchange may liquidate the excess.

Polymarket US's rulebook, dated 30 September 2026, puts it more briefly in Rule 5.9(a): no person may enter into a transaction that would cause it to exceed a position limit, except that the exchange may, on application, exempt a participant "for hedging or other good cause shown", with new limits of its own and the right to rescind them.

A position accountability level is a tripwire

Kalshi's rulebook defines a Position Accountability Level as the level of loss "above which Kalshi may impose restrictions or obligations on the Member". Under Rule 5.18 a participant above it must give the compliance staff whatever information they consider necessary, and must "refrain from increasing the size of their position or reduce the size of their position in a timely fashion if instructed to do so". If the reduction does not happen, Kalshi may liquidate the position down to the level, or to a limit it imposes on that participant.

Polymarket US defines its level as the size of positions "above which a Participant holding the positions is required to submit reports". Rule 5.9(b) lets the exchange ask for the nature and size of the position, "the trading strategy employed", and anything supporting a claim that the position is a hedge, and to order a reduction from a participant who fails to answer or to order that a position above the threshold not be increased.

Nothing in either rulebook stops the order that takes you over an accountability level. What changes is that the position is now the exchange's business.

Kalshi moved most contracts from one to the other

On 14 November 2024 Kalshi notified the CFTC that it was replacing "Position Limit" with "Position Accountability Level" for every contract listed in the filing's appendix, effective no earlier than 27 November 2024 and alongside rulebook amendments adopting accountability rules. The appendix sets 25,000 contracts for most of the listed contracts, and 7,000,000 for fourteen of them: seven on the Federal Reserve and economic data, seven on nominations, confirmations and appointments to office. The reasons given are that accountability levels let Kalshi "take more holistic views of its members' risk exposures" and that "other event contracts exchanges use position accountability instead of position limits".

Not every contract moved. The CONTROL terms for which party controls a chamber of Congress, as posted in Kalshi's contract-terms store on 23 October 2026, still carry Position Limits, in three tiers:

• individuals, $125,000 per member, or $250,000 with a demonstrated hedging need;
• entities, $5,000,000, or $10,000,000;
• eligible contract participants, $50,000,000, or $100,000,000.

Whether a hedging need has been shown "is determined solely at Kalshi's discretion".

Market makers get more room

Kalshi's Rule 4.5 gives market makers accountability levels ten times those of other members on contracts where they have quoting obligations, unless otherwise specified, and exempts them from position limits on those contracts. The filing of November 2024 explains why: a quoter who has to keep two-sided prices up will otherwise run into the level just by doing the job. Polymarket US's Rule 4.3 lists "different Position Accountability Levels" among the benefits a market maker programme may confer. Kalshi's Rule 4.5(c) adds that a market maker's position may never exceed a limit the CFTC itself has set. Who is paid to quote covers what the quoter owes in return.

What the number is counted in

Three things vary, and a number quoted without them cannot be compared with anything.

The unit. Kalshi's definitions measure both thresholds as a level of loss. Its November 2024 filing rewrote the example clause from "$25,000 per strike" to "25,000 contracts per strike"; on a contract that pays $1, the most a contract can lose is under $1, so the two are close but not the same. Its FOOTBALLSTATS combo terms, in turn, set "$25,000 per strike, per Member". Polymarket US's filed combo terms set "$25,000 of notional exposure". OG's Fees & Limits page, dated 15 September 2026, gives 2,500,000 for a contract value of $1, defined as "the maximum total number of open positions you can hold for the same event".

The scope. Per strike means per market inside a series: one threshold for each price or outcome line. Per event, as on OG, covers every market attached to the same event together. Per member means per account holder, and both US rulebooks then aggregate.

The aggregation. Kalshi's Rule 5.19(f) applies limits to all accounts in which a person "directly or indirectly holds positions or controls trading", and to positions held by two or more persons acting under "an express or implied agreement or understanding", as if one person held them. Polymarket US's Rule 5.9(a) aggregates accounts as CFTC Regulation 150.4 provides.

PredictIt's row comes from a different kind of document. It operates under a CFTC no-action position rather than as an exchange, and CFTC Letter No. 25-20 of 14 July 2025 sets "the investment limit for a single participant in any particular contract" at the federal limit on individual campaign contributions per election, per candidate, which the letter gives as $3,500 and the Federal Election Commission adjusts every two years.

An order cap is not a position limit

Polymarket US's Trading Limits page says a single market buy in the app or on the web is limited to $1,000,000, and that combos have their own maximum stake. That caps one order, not what you may own; the rulebook separately lets the exchange set a maximum order size per account from the funds available and the account's trading behaviour.

What you can do about it

Read the line in the contract's own terms. Every contract's terms carry either "Position Limit:" or "Position Accountability Level:", and on the two US exchanges read here that one line is where the number is stated. The rulebook tells you what happens when you reach it; the terms tell you where it is. A help-centre summary may lag a refiled contract.

Convert the number to your own unit before you size anything. A threshold in dollars of loss, one in notional and one in contracts give three different answers for the same position, and a per-strike level is not a per-event one.

Count every account you control. Splitting a position across accounts, or across people who trade by agreement, does not reset the count on either US exchange.

Expect questions above an accountability level, not a rejection. Have the answer the rulebooks ask for: what the position is for, and whether it hedges something. A hedging exemption from a limit has to be applied for and is granted at the exchange's discretion; it is not assumed.

Treat order caps and position caps as two checks. An order may be refused for size while the position it would create is within every limit, and the reverse.

The venue cards for Kalshi, Polymarket US and PredictIt carry the rest of each venue's terms; multi-leg contracts and their own thresholds are on what a combo contract is.