Can't execute fractional orders during extended trading hours?

[lukmisch]

Hello! I am having difficulty executing fractional limit orders during extended trading hours. I have Gold and would like to utilize extended trading in my code. I've tried order(), order_buy_fractional_by_price(), and order_buy_fractional_by_quantity(), being careful to pass the correct parameters for extendedHours and market_hours.

These work for regular hours, but returns this for extended hours orders:
{'non_field_errors': ['Limit order quantity cannot include fractional shares.']}

I find this odd because I can execute fractional limit buys from my phone or Robinhood website during extended hours. Why isn't it working via my code?

Here is a test payload of $1 of TSLA I am sending before calling request_post() via Robin Stocks. I removed the account field for security:

{
  'instrument': 'https://api.robinhood.com/instruments/e39ed23a-7bd1-4587-b060-71988d9ef483/',
  'symbol': 'TSLA',
  'price': 355.5,
  'ask_price': 355.5,
  'bid_ask_timestamp': '2025-02-13 17:16:05.612863',
  'bid_price': 355.39,
  'quantity': 0.00281413,
  'ref_id': 'de24b474-7843-402b-a730-61010ae3dffa',
  'type': 'limit',
  'time_in_force': 'gfd',
  'trigger': 'immediate',
  'side': 'buy',
  'market_hours': 'extended_hours',
  'extended_hours': True,
  'order_form_version': 4
}  

I've noticed that when sending payloads through Robinhood website using Inspect Element to monitor network traffic during extended hours for successful fractional limits, there are a lot more fields in the payload. Not sure if that plays a factor or not.

[Adelantado]

It's been a while since I looked into this but as far as I remember, only whole shares not fractional, will get queered and processed during extended hours.
Fractional shares will either fail / get rejected, or queered till next day market opening, not sure.

[lukmisch]

It's been a while since I looked into this but as far as I remember, only whole shares not fractional, will get queered and processed during extended hours. Fractional shares will either fail / get rejected, or queered till next day market opening, not sure.

Right. The orders are getting rejected unless it’s whole shares. But I can execute fractional limit orders during extended hours via the website and on my phone Robinhood app perfectly fine, so perhaps there’s a way to send an HTTP request with the Robin Stocks api to do it through code as well?

[Adelantado]

Yes, U are right, I saw something funky about it too. Never got that involved with after hours trading due that same reason.

I would share that if for A or B, if a fractional order does not get executed before 4 pm, I cancel it as I do not want it lingering till market opens next morning.

I do place some after hours trades when in need ( always whole shares ), but they are set up manually and submitted thru the app; didn't know you could set up after hours fractional manually. Thanks for the tip !