Gap shares were down more than four percent in extended trading following the earnings announcement — and all this, just ahead of the critical holiday retail season. (businessoffashion.com)
I'm not sure about the options exchanges; they're not regulated the same way and are a good example of exchanges with extended trading hours in the first place. (money.stackexchange.com)
Most brokers require traders to enter limit day orders during extended trading sessions since the lack of liquidity makes market orders impossible in some cases. (investopedia.com)