Bitcoin's price typically experiences upward momentum both before and after a halving event due to several factors:

1. **Anticipation**: Investors often buy Bitcoin in anticipation of the halving event, expecting a reduction in the rate of new supply issuance. This increased demand can drive up the price.

2. **Supply Reduction**: The halving reduces the rate at which new bitcoins are created, cutting the supply. With a decreased supply and assuming demand remains constant or increases, prices tend to rise due to scarcity.

3. **Market Sentiment**: Positive sentiment surrounding the halving, such as media coverage and increased interest from retail and institutional investors, can contribute to price appreciation.

4. **Historical Precedent**: Previous halving events have been followed by significant price rallies, leading some investors to expect a similar pattern to repeat.

5. **Miners' Behavior**: Miners may hoard more bitcoins or increase their asking prices to compensate for the reduced block rewards, further reducing the available supply and potentially driving up prices.

After the halving, the reduced supply gradually becomes more apparent in the market, reinforcing the scarcity narrative. However, it's essential to note that market dynamics are complex, and other factors, such as macroeconomic trends, regulatory developments, and technological advancements, can also influence Bitcoin's price movements.