Power hour — roughly 3:00 to 4:00 PM ET — is the final hour of the regular session, and it trades nothing like the sleepy midday. Volume surges back, positioning resolves, and moves accelerate.

Why it comes alive

Two forces converge. First, volume returns — funds rebalance, day traders close or press positions, and the day's conviction shows up in the tape. Second, on expiration day, 0DTE gamma peaks: same-day options are hyper-sensitive to price now, and dealer hedging of that exposure can amplify the closing move (why gamma matters for 0DTE).

Opportunity and danger

The speed cuts both ways. A trend that's held all day often makes its strongest push into the close — great if you're aligned, brutal if you faded it. And in a negative-gamma regime, the amplification can turn an orderly afternoon into a violent one (how dealer hedging moves price). Wider swings mean position size should be smaller, not larger.

Power hour pays the aligned and punishes the stubborn. It's the fastest hour to be right — and the fastest to be wrong.

Trading it sanely

Respect the increased volatility with tighter risk and smaller size, trade with the day's established structure rather than against it (intraday trend following), and if you're on 0DTE, remember the force-flat rule — nothing held into the close (0DTE risk management). See the best time of day to trade 0DTE.