I have data that looks something like this:

Array

It is market cap data for different companies, starting from 1 jan 2009 to 1 july 2021.
For some days, there is no data. I would like to create rows for all missing dates for each company with its last available market cap.
Some companies only existed for example from 2005 to 2008, so these don't need dates added before 05 and after 08, but if they are added I don't think it will be a problem for how I'm using the data.