What happens at 8 am ET that makes the 8:00 - 9:30 time period normal versus 4:00 - 8:00? Does something technically differ between the two time periods or is it just the fact that volume is higher during the last 1.5 hours? I can see that Interactive Brokers allows trading from 4 am whereas e.g. Charles Schwab only allows trading from 8 am. https://www.investorsunderground.com/pre-market-trading/
When you can look it up on a regulatory or exchange website, it's *probably* real. When it's hung in quotes, like "Normal...", it's probably an artifact of history. This one ("Normal Pre-Market") is an artifact. If you watch the overnight or pre-market volume, you'll notice spikes on news events (100-1,000 contracts, for example). For big data drops, you might notice one or two minutes where volume approaches that of the regular cash-market (say, 2,000-5,000). As CyJackX noted, it's when big reports drop. When the market opens, it might be 10,000-20,000 for 15 minutes, and then the dust would settle to a quarter of that. Nothing set in concrete about it, but somebody wanted to attach a word. So they used an older pre-market, noted the remaining higher volume, and "Hey! Here's 'Normal'!!"
%% Its like an elitetrader said '' premarket, where do you[ we ]want the price ??'' LOL[REAL-TIC named those ''irregular hours'']