The brokerage can offer various per market sessions. Some brokerages may not let you trade in the extended market hours. So make sure that you check if your brokerage firm lets you trade during the premarket and the post-market sessions.
Some brokerage firms may just charge the regular fees and commission whereas other brokerage firms may charge you additional rates. You need to find this from your brokerage firm before you open an account with them.
There are some benefits of trading before the market opens. This will let you enter into a trade based on the news or an earnings report that had come out after the last trading day. If you wait for the market to open to place your trades then you may not be able to place a trade in the volatility and may miss out on a trade. Thus trading in the premarket lets you react to news or an event faster.
There are some risks involved in trading during the premarket session. The major risk in trading in the premarket session is that of liquidity. The number of sellers and buyers would be less during the premarket session and thus you may not get a very competitive rate to buy or sell your shares. The volatility is huge during the pre-market session especially in cases when there is learning or news release about a particular stock. The spread is huge in the premarket session and thus you should be ready to pay extra. You need to be aware of these risks to place trades in the pre-market session.
The electronic communication network lets you trade in the extended market hours. So when you select a brokerage firm, make sure that you check with them if they allow you to trade in the pre-market session. Each firm may have their own rules and hours to trade.
Trading during the pre-market session is easy. All that you need to do is to select which stock you would like to buy or sell. Enter the stock symbol and click on buy or sell. Enter the number of stocks that you would like to buy or sell and then place the price that you would want the stock to be executed at. For this make sure that you check the bid/ask price. You will have to use a limit order if you want the trade to be executed on Ethereum Code.