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?
That's Bitcoin's volatility for you. This type of price drop is very common so get used to it. This occurs from time to time even though there is no significant reason at all. In this case, it is clear that it is just a correction. We just witnessed a new all time high days ago at around 6,100 USD so it is just normal to see Bitcoin go down a bit. This may be caused by some people selling their coins to get some profit.