Why is there a gap in closing and opening prices on this chart for FB? The previous close on Feb 2 is 323.00 and Feb 3 opening is 244.65. Shouldn't the previous day's close be the next day's opening?
There is no requirement that yesterday's closing price be today's opening price. The two figures are unrelated.
Yesterday's closing was the last trade price for the stock. Basically it's a historical representation of what happened then.
Today's opening is where trading started. In the case of FB there was some news that investors considered to be bad announced AFTER yesterday's close. So yesterday's traders were unaware of it. When trading started today investors considered the news and felt the stock was NOT worth what it was worth yesterday and the opening price is significantly lower.