Alpaca API Order Rules for Automated Trading (2026): Fractional Shares, Brackets, Time in Force, Extended Hours, Paper Accounts and Limits
Alpaca's API is the most permissive of the stock brokers JorgAI connects to: fractional shares, dollar-sized orders, broker-held brackets, crypto in the same account and a real paper account. It also has the most rules about which combinations are allowed, and an automated order that breaks one is rejected rather than fixed. This page lists the rules as Alpaca's own order documentation states them (page updated October 13, 2026) and as JorgAI's integration applies them, verified from the integration code on November 6, 2026. For the same rows across all six connected brokers, see the broker API capabilities page.
The rules in one table
| Rule | What Alpaca allows | What JorgAI sends |
|---|---|---|
| Order types | Market, limit, stop, stop-limit; bracket, OCO and OTO order classes; trailing stop as a single order | Market, limit, stop and stop-limit; dollar-sized market buys; brackets on equity market buys |
| Time in force | day, gtc, opg, cls, ioc, fok for stocks; crypto takes gtc and ioc only | Day by default or gtc for stocks; crypto always gtc; brackets as day orders |
| Fractional orders | Day time-in-force only, on market, limit, stop and stop-limit orders; gtc, ioc, fok, opg and cls are not allowed for fractional quantities | Fractional sizes to four decimals with a 0.001-share minimum, on stocks Alpaca marks fractionable; a fractional size on a non-fractionable stock is skipped, not rounded up |
| Brackets | Require day or gtc; extended hours not allowed; each leg carries a do-not-reduce instruction; the take-profit leg must be a limit | A take-profit limit and a stop loss as OCO legs on an equity market buy. If Alpaca answers that the stock is not fractionable, the size is floored to whole shares and the bracket kept; if it requires a simple order for a fractional size, the bracket is dropped and JorgAI's monitor manages the exits |
| Trailing stops | Supported as single orders, day or gtc; do not trigger outside regular hours; not available as bracket or OCO legs | Run in JorgAI's monitor at every broker, so the trailing rule behaves the same on Alpaca as elsewhere |
| Extended hours | Limit orders with day or gtc only, with the extended-hours flag set; pre-market 4:00 to 9:30 AM ET, after-hours 4:00 to 8:00 PM ET, overnight 8:00 PM to 4:00 AM ET | Not used; stock orders go in during the regular session. Crypto trades around the clock |
| Price precision | Two decimals at or above $1.00; four decimals below $1.00 on limit and stop prices | Prices are rounded to the allowed precision before sending |
| Aged orders | Good-till-cancelled orders are cancelled by Alpaca 90 days after creation | Exit legs that outlive a position are reconciled and replaced by the monitor |
| Paper account | A separate paper environment with its own keys | A paper connection routes to the paper API; the only member-facing paper account among the six brokers |
| Price feed | IEX feed on the free data plan; SIP on paid plans | Alpaca's IEX feed for decisions, exits and position values; the bid-ask midpoint when the last trade is more than a minute old |
What the rules mean for an automated account
Fractional shares, with one catch
Alpaca fills fractional orders only as day orders and only on stocks it marks fractionable, which is most large US stocks and ETFs but not all of them. JorgAI sizes to four decimals with a floor of a thousandth of a share. When Alpaca reports that a stock is not fractionable, the order is floored to whole shares; if that leaves less than one share, the order is skipped rather than rounded up, so a small budget never buys more than it was told to.
Brackets, and when they are dropped
A bracket places the take-profit and stop-loss at Alpaca as one-cancels-other legs, so the exits exist on the broker's servers even if JorgAI is unreachable for a while. Alpaca requires a simple order for some fractional sizes; in that case JorgAI sends the entry alone and its own monitor manages the exits on a short cycle. Either way the trailing stop runs in the monitor, because Alpaca's trailing stop cannot sit inside a bracket. What that means during an outage has its own page.
Crypto in the same account
Alpaca takes gtc and ioc only for crypto, so JorgAI sends crypto orders good till cancelled and the exchange-style rules for crypto (fractional sizes, round-the-clock trading) apply inside the same account that holds your stocks. Brackets are stocks only.
Paper first
Alpaca is the one stock broker here with a member-facing paper account. A paper connection in JorgAI routes every order to Alpaca's paper API with the same code path as live, which is why the paper-trading guide recommends a week on paper before switching the connection.
Quick answers
Does the Alpaca API support fractional shares?
Yes, on fractionable stocks, as day orders on market, limit, stop and stop-limit types. Not with gtc, ioc, fok, opg or cls.
Can an Alpaca bracket order be fractional?
Alpaca's documentation does not say. In practice Alpaca rejects some fractional bracket orders with a request for a simple order, which is why JorgAI drops the bracket and manages the exits itself in that case.
Does Alpaca trade after hours through the API?
Yes, limit orders with day or gtc and the extended-hours flag, in three sessions covering 8:00 PM to 9:30 AM and 4:00 PM to 8:00 PM ET. JorgAI does not use them; stock orders go in during the regular session.
Does the Alpaca connection expire?
No. A key connection lasts until you revoke the key; an Alpaca Connect sign-in issues a token that does not expire.
How we put this together. The Alpaca column comes from Alpaca's Placing Orders page, read on November 6, 2026 (the page shows an October 13, 2026 update). The JorgAI column comes from a line-by-line read of the Alpaca adapter and auto-trader workers the same day. For the setup steps, see how to automate an Alpaca account; for the platforms that connect to Alpaca, the Alpaca bots comparison.
To see a rule run on an Alpaca paper account before you connect a live one, start on the free plan.
Schwab's June 2026 fractional-share expansion, the old Stock Slices rules and why the Trader API still trades whole shares are on the Schwab fractional shares page.
The figures in this article describe broker API behaviour and are not a prediction or a recommendation to buy or sell any security or digital asset. JorgAI is software that carries out the rules you set in your own brokerage or exchange account; it is not an investment adviser. Trading involves risk of loss.
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