Catalyst supports three order types accessible from the drop-down in the order ticket. Choosing the right one depends on whether speed or price matters more to you.
Buy in dollars (market order)
You enter the dollar amount you want to spend
Contracts are calculated automatically based on available prices
Executes immediately using available liquidity
Final price depends on what is in the order book — may fill across multiple price levels on larger orders
Buy in contracts (market order)
You enter the exact number of contracts you want
Same execution behavior as Buy in dollars — just sized differently
Useful when you want a specific number of contracts rather than a dollar amount
Limit order
You set the exact price you are willing to pay (for buys) or accept (for sells)
Only executes if the market reaches your price
Gives you price control but may not fill if the market never reaches your price
Limit orders have two duration options:
GTC (Good 'Til Canceled) Stays open until it fills or you cancel it. Use when you are willing to wait for your price.
IOC (Immediate or Cancel) Fills immediately at your price if liquidity is available — cancels anything that does not fill right away. Use when you want your price but do not want an open order sitting.
When to use each
Order type | Best when |
Market order (dollars or contracts) | Execution speed matters more than price precision — you want in now |
Limit order | You have a specific price target and are willing to wait (or miss) to get it |
Choosing between a market order and a limit order comes down to one question: do you need to be in the trade right now, or do you need to be in at a specific price? If speed matters, use a market order. If price matters, use a limit order and be prepared for the possibility that it does not fill.
Why is my Buy button grayed out on a limit order?
Two things are required before the Buy button becomes available: a contract quantity and a limit price. If either field is empty or zero, the button stays disabled.
If both fields are filled in but the button is still grayed out, the issue is almost always the limit price. For the order to go through, your limit price needs to match what the market is actually offering:
Buying YES — set your limit price at or above the current YES ask price
Buying NO — set your limit price at or below the current NO ask price
Example: YES contracts are currently priced at 93¢. If you enter a limit price of 50¢, the Buy button won't activate because no one is selling at that price. Change your limit price to 93¢ or higher and the total cost and payout will populate, unlocking the Buy button.