@ALRAZEEN, some fundamental reasons that could signal a market downturn include- Trade war tensions building and we are approaching an inverted yield curve which could signal a recession is ahead, as rates keep rising this will affect consumer debt, which is at insanely high levels, just take a look at auto loans, mortgages, student loan debt. All we need is a trigger to get things kicked off, which could be any number of these things or something else unexpected. Not to mention after a 10 year bull market this feels very toppy right now.
I would recommend taking a look at this Wyckoff analysis for a very nice detailed TA of the possible upcoming crash