Bitcoin price is finding it hard to stay above $4200-4100 against the US Dollar. More declines towards $3900 is likely in BTC/USD in the near term.

Key Points
1. Bitcoin price is struggling to remain above the $4100 support area against the US Dollar.
2. There is a key bullish trend line with support at $4150 forming on the 4-hours chart of BTC/USD (data feed from SimpleFX).
3. The pair is heading towards the trend line support at $4150 and might attempt a downside break.

Bitcoin Price Crucial Support
There were a couple of swing moves in Bitcoin price towards $4500 against the US Dollar this past week. The price declined on a couple of occasions, but the $4000-4100 support area held the downside. The price recently recovered from the $4018 low. It traded above the 50% Fib retracement level of the last decline from the $4966 high to $4018 low. It even moved above the $4500 level and the 100 simple moving average (H4).

However, the upside move faced sellers near $4650. Buyers failed to place the price above the 61.8% Fib retracement level of the last decline from the $4966 high to $4018 low. The price moved down and traded below the $4500 support and the 100 simple moving average (H4). On the downside, there is a key bullish trend line with support at $4150 forming on the 4-hours chart of BTC/USD.

Source: http://www.newsbtc.com/2017/09/10/bitcoin-price-weekly-analysis-btcusd-breakdown/

After bitcoin reach $5000, who want to sell below $4500? Unless, you are daily traders or desperately need for money.
If bitcoin remain fluctuate and downtrend keep showing up, people will tend to hold or sell but actually it is a good price to buy more bitcoin.
We know bitcoin will recover and reach $5000 again, just time matter whether it would be few days later, next week or next month.