oren, small margin calls work the way you suggested. But in this case, it is a significant margin call that the account owner didn't meet by the deadline. It is very normal for a broker to sell at the end of the trading day to meet a margin call because the account holder has missed the deadline.
I am just relieved it that the trade is not due to VB-111 or VBLT - or at least it doesn't seem like it after the stock rebounded. Onward to the press conference ...
News 
Market Data 
Discover 
