This property reflects the value of the matchTimeout parameter of the RegexMatchTimeoutException.#ctor(string, string, TimeSpan) constructor. If the parameter is not properly initialized in a constructor call, its value is Timespan.FromTicks(-1).

The value of this property reflects the time-out interval set in the call to the System.Text.RegularExpressions.Regex constructor or static method. It does not reflect the exact interval that has elapsed from the beginning of the method call to the time the exception is thrown.