The percentage change showing on marketwatch isn’t right when I compare the last traded price to previous closing price. Why?
The change in price and percentage will be shown based on the preference in the marketwatch settings. If the percentage change is set to Open price, it may not match with the percentage change when compared to the previous Closing price.
The percentage change is calculated using the previous day's close by default. This can be changed to the open price from the marketwatch settings.