The top of the hour has its own gravity

[Fairman]

The top of the hour has its own gravity

Many algorithms and fund flows are scheduled on the hour or half hour. Fixes, rebalancing trades, and time-weighted execution programs all tend to cluster at round clock times, and the market shows small bursts of activity at those moments.

On a one second chart, a spike in tick volume appears at the :00 and :30 marks, with sometimes a small price jerk. It is rarely large, but it can be enough to disturb a tight scalp.

The effect is strongest in the busiest sessions and at specific hours like 10am New York, 4pm London, and the opening of major markets.

A scalper holding a position through those moments faces slightly more volatility than the average second. Tight stops get tested, and entries placed seconds before the hour can be caught in the burst.

A habit worth testing is avoiding fresh entries in the 20 seconds before the hour and half hour, and seeing whether the results change. Some find a small but consistent improvement.

One small test: bucket the one second returns by seconds past the hour, and compare the average absolute move in the first five seconds of each minute with the rest of the minute. A visible hump near :00 and :30 confirms the effect on the broker's own feed.

Does the strategy show any difference in performance around round clock times?