Execution desks at large institutions are graded on whether they bought below the day's average or above it. When a fund must buy size, it leans in while price is under the line and holds off when it's above. The result is that the line behaves like a real level — not by magic, but by the aggregate behaviour of whoever moves the market.

The basic read: price above the line — buyers control the day, look for long entries on dips back to it. Price below the line — sellers control, and a long is swimming against the day's current.

The first is entry: a stock trending up that pulls back to the line, touches it and turns — stop just under the line, small and defined risk. The second is defence: if you're long and price breaks under the line and stays there, the assumption that buyers are in control is no longer true, and there's no reason to hold.

One warning that saves money: in the first minutes the line moves fast and jumps around, because it rests on very little data. It becomes reliable and stable only once trading settles, roughly after the first thirty to sixty minutes.

The line predicts nothing. It doesn't say the stock will rise and it isn't a buy signal in itself. It gives a frame: where the majority sits, and which side you're standing on. Like any level, it breaks easily on a day with strong news.