Unless you’re swing trading stocks, you’ll close out your positions. Day trading means you’re getting in and out of trades quickly. As a result, if you took a position before trading slowed down, you will want to close it out before the end of the day.
That means come 3 pm, traders want to get out of positions. Another thing to consider is that anyone wishing to avoid the PDT rule will come in to buy a stock to hold overnight.
Hence, the buying and selling that picks up with power hour stocks. Volatility is important to trading. Without it, you don’t get price action. End of day trading can help to grow your brokerage account.