What happens when a stock hits VWAP?

When a stock hits VWAP, it typically reacts because traders treat the level as fair value and dynamic support or resistance.

If the stock is trading above VWAP and declines toward it, bulls defend VWAP as support.

If trading below VWAP and rising toward it, bears short against resistance to keep the stock below this level.

A clean break flips control, since a break of significant resistance causes bearish traders to close shorts and bullish traders to establish longs, creating a sudden influx in trading activity.
Reactions are strongest on liquid, high-volume names where the level becomes self-fulfilling.