A number of reasons can cause your stock order to be canceled or rejected. The following are some of the more common reasons why.

• Your order was routed to a broker that can’t accept it: An order might be routed to one of our executing brokers that can’t accept it. If this happens, simply reenter the order, and one of our stock brokers will make sure it gets routed appropriately.
• Your limit order is too aggressive: A limit order may also be rejected if it fails one of our risk checks. Risk checks help us to identify orders that don't quite make sense in the context of where the stock is currently trading in the market, such as a $1,000 limit sell order for a stock currently trading at $5. This means that your order may be canceled if the price of the security moves significantly away from your limit or stop price and is then seen as too aggressive.
• You incorrectly placed a stop order: A stop order triggers a market order or a stop limit order triggers a limit order once the stock reaches your stop price. However, if you set a stop order for a stock at its current price, we’ll reject your order. Additionally, if you set a stop order that would execute immediately (e.g. a buy stop order below the current market price or a sell stop order above the current market price), we’ll reject your order.
• The stock executed a split: If a stock undergoes a reverse split, we’re required to cancel all open orders.
• Margin call risk: Your Good-til-Canceled (GTC) buy orders could be canceled if your investing account doesn't have enough buying power to support them. Buying power is the amount of money you can use to purchase stocks, options, futures, or crypto. You may have negative buying power if your portfolio value drops below your initial margin requirement. While having negative buying power doesn't necessarily mean that you're in a margin call, we cancel these orders because they would put you at a much higher risk of a margin call.