Believe from my knowledge what someone else did, that you can short anything,
if you can get a broker - and it wont be Barclays cause they refused him,
to sell shares that you dont have to buy them back at a later date, although the guy was a bit naughty as he didn't tell them that he didn't have a cert. although the end result was he did make a lot of money from buying them back somewhat later.
See someone sold 223k they must need the money for something or are just not up to speed with events. We don't want unknowledgable investors feeding the MM with stock.