Dan Passarelli, CEO - Market Taker Mentoring 

Following a big up day in the US stock market following the Federal Reserve decision to raise the discount rate 50 basis points, stocks fell hard today. They wiped out all of yesterday's gains and then some. They're trading lower than yesterday's low and are sitting at a key support level. If the market breaks this support level it might continue lower.

Support is a technical study on a stock chart that shows a horizontal line at which a stock fell to and bounced back higher off of several times. Typically a support line indicates that's where the buyers have their stock buy orders in and often that built up buying pressure forces the stock higher.

When a support line is crossed, meaning the stock falls below it, there can often be downward momentum to follow.