When dealing with stocks, what does premarket mean?

There is pre-market, market & after-hours. Most retail investors only participate in the “market hours” trading during 9:30a EST to 4:00p EST.

There are 3 trading hours, pre-market, market and after hours trading. Most trades I know, including myself typically watch those times, but don’t typically trade them because the volume is so low. You can watch companies earnings shoot up or down during pre-market and after-hours trading before normal market hours open to gauge the market reaction to earnings conference calls.

I’ve attached a screenshot of the S&P500 etf (SPY) illustrating this for you. You can see “After hours yesterday”, the price dipped a little and recovered. You can see “Pre-market today” the price went down and once the market opened (“market hours today”), it shot up. Hope that helps.