I just checked poloniex today and btcprice went don't to $5506.28 so that would be -$500 dive. Is this because of the upcoming fork? Can somebody enlighten me what could be causing this?
You're definitely right. The decrease on its market value might be caused by the incoming hardfork in November. As the month is getting closer Bitcoin's value is having difficulties with the increase on its value. It is now tied between 6000 and 5500. There's also a probability that it will fall under 5500 but there's no need to qorry because eventually, or after the segwit2x it will again increase and be more expensive.