Lucsan001-You will have to ask TDA if that value is the change from the last sale on any day to the last sale on that day or some other metric. The reality is that this column does not provide real actionable information on deep ITM options that do not trade all day and when the last sale does not represent the current market because the last sale could have been days ago. For myself, I would be more apt to follow changes in IVOL with ATM options from one day to another or overtime. The next metric I find value in is the option skew. I like to follow the 25 delta call and 25 delta put. Following the (put-call) gives a metric to watch that shows changes in supply-demand for puts over calls. I find this has more value with options that are not short term in nature like less than 1 week.
