Yes you can! PHP has all the same logical constructs as VBA, just the syntax is different. VBA program flow will translate to PHP just fine. It'll be a struggle at first to learn PHP syntax, but at least you know how to program in general, it will serve you well.
Most of the work could actually be assembling the FTSE 100 data into a form usable by PHP. If the data is available in one place, whatever the form, you can probably concoct a translation routine that can pluck the necessary data out of the document or DB table and use it to assign to variables in creating posts and saving each to the WP DB.
Let's say you've managed to assemble the data into a PHP array somehow. Then just run a foreach loop driven by each company. Assemble all pertinent data into a post data array which is then fed to wp_insert_post() to save in turn each company's post to the DB.