Before revision:  In our non-concave optimization problem, we find that  for any VaR-constraint with an arbitrary risk level, there exists an ES-constraint leading to the same investment strategy, assuming that the regulation only protects the debt holders' benefit to a certain level .
After revision:  In our non-concave optimization problem, we find that for any VaR-constraint with an arbitrary risk level, there exists an ES-constraint leading to the same investment strategy, which shows on some level the ineffectiveness of the ES-based regulation .