twAlthough the paper trading account replicates most aspects of a production TWS account, you may encounter some differences due to its construction as a simulator with no execution or clearing abilities. These differences include but are not limited to: No support for some order types including: Passive Relative, Auction, RFQ, Pegged to Market and Market with Protection (for futures directed to Globex).

Fills are simulated from the top of the book; no deep book access. Limited combo and EFP trading. Stops and other complex order types are always simulated in paper trading; this may result in slightly different behavior from a TWS production account.Penny trading for US Options is not supported. You will be able to submit the order but it will not receive a penny fill.

The trade simulator will reject the remainder of any exchange-directed market order that partially executes. This may or may not match behavior of a real-world exchange. Market orders received while there is no quote on the opposite side will be held until the market data arrives (i.e. until the first partial fill). Mutual Fund trading is not supported.

Additional information on: paper trading accounts and executions on paper trading accounts can be found in our Users' Guide and Knowledge Base.