Alpaca currently supports fractional trading for market and day order types (support for other order types are in our roadmap). You can pass either a fractional amount (qty), or a notional value (notional) in any POST/v2/orders request. Note that entering a value for either parameters, will automatically nullify the other. If both qty and notional are entered the request will be rejected with an error status 400.

Both notional and qty fields can take up to 9 decimal point values.

Sample Fractional Order Requests

Notional Request

{
  "symbol": "AAPL",
  "notional": 500.75,
  "side": "buy",
  "type": "market",
  "time_in_force":"day"
}

Fractional Request

{
  "symbol": "AAPL",
  "qty": 3.654,
  "side": "buy",
  "type": "market",
  "time_in_force":"day"
}