Kernrechtsfrage
Whether the bank's damage claim was sufficiently substantiated
Extrahierter Entscheid
The claim was not sufficiently substantiated because the customer did not explain the difference between her actual asset position and the position that would have existed under proper performance.
Extrahierte Begründung
A mere assertion of investment loss is not enough; in portfolio cases the claimant must present facts allowing the court to estimate damages, including the hypothetical development of a properly composed portfolio.