Last year there was a similar case in Germany with PAIM in August.
There were so many shareholder short, cause a member of Penson didn`t told it early enough that there will be a revers split.
Millions and millions where short, cause they sold all their shares (they had had all shares in their account. A few broker in Germany and Austria didn`t restricted the permitted contigent.
They said to the shareholder: "No, you can sell all your shares" LOL
2 or 3 days later were a trading halt only in Germany. In US were no trading halt. The tradinghalt was 3 days long.
Than the broker told to everybody that they have to cover in next 14 days.
Many shareholders had many bead of sweat cause the price were exploded.
Some had covered expensiv.
After the 14 days were nothing. A man of Penson accepted a blame. That was all
The broker just made fluff.
If IB or another broker forced you short that would be a similar case.