My apologies if this seems like a really ignorant...

My apologies if this seems like a really ignorant question....what is the significance of all the buying and selling by UBS and related groups from the 17th to the 25th March, with multiple transactions, both buy and sell, on the same day? I am referring to the "ceasing to be a substantial holder" notice on 25th March. My first thought was to wonder whether this was short selling but I have never short sold before so have no idea how to do it, so it's probably not...if not then what benefit is to be gained by such frantic activity? Thanks for any insights...