1. Media person shorts stock
2. Media person tells viewers stock is worthless
3. Viewers holding stock get nervous, sell shares
4. Stock price goes down, media person cashes in.
I do think it is a bit unfair to say they need to hold their investments in a blind trust, but definitely agree that disclosures about their positions should clear and abundant.
I think there's actually a case to be made that that sort of financial journalism would be much better than the veneer of impartiality that we have now.
I would find Bloomberg articles much more compelling if I knew that their authors had personally invested in their truth. At the very least, it'd quickly weed out the ones who are regularly wrong. And, if they cited the amount of their investment, it'd give you a proxy for the strength of their own conviction. All extremely critical data that you can never fully attain from prose alone.