Fiduciary duty is alive and well at Etrade--the duty is to themselves and the opponent is the client base.
Their margin department refused to disclose their basis for required margin adjustments. They drastically raised the required collateral (in one case, leverage moved from 4X to 1.5X overnight). When I requested information on historical margin call alerts, they claimed to delete records after six months.
The margin calls are OPPORTUNISTIC. They were not dependent upon day-to-day or trending volatilities. The initial margin was generous, and the portfolio volatility low. However, Etrade's margin department prepares for moments when they can profitably call against you. When they do, be sure that they are your trading partner on the other side.