The big tech stocks have led the US markets ever higher and valuations as a whole for this subgroup look, to me, to be stretched. But I have been saying that for a while so you may choose to ignore what follows. However, while I have compared shorting such enterprises to standing in front of an oncoming express train waving your red flags, is there now a case for shorting Twitter? At $47.42, the market cap is $37.8 billion.