Pre-market trading takes place from 8:15 a.m. to 9:30 a.m., right before the market opens. The standard time for market opening is 8:00 a.m. The extending trading data can be seen on a 15 minute deference basis.
One important thing about pre-market stocks is that this trading is shown only if the stock is a part of Nasdaq-100 index. Investors realize that that pre-market Nasdaq-100 trading is a good resource for an indicator for trading that takes place in regular hours.
One good thing for investors is that they can utilize this data to evaluate the advantage of buying in the stock when regular market is just opened. In addition to it, they can also use this bunch of information such that they cab judge the pre-market activity i.e. opening price of some stock and how far the market is likely to support stocks.
As the trading is done in such a market before the regular market opens, the participation by ECNs and market makers is intentional. As a result, somewhat less liquidity can be observed in pre-market trading as compared to normal trading hours. The concept to play in such market is to use a limit order. Most people highly recommend a limit order in such a case.
So, in short stocks can be bought in pre-market easily with the help of ECN, an electronic system that completely removes the dependency on the third party. So, this connects individual traders and major brokerages and enables them to trade directly without any interference.