NPN transistor negative base voltage

basebjtnpntransistors

In this circuit, when I switch off the transistor opening the switch SW1, a negative Voltage of circa -6.5V appears at its base.
I would like to understand why, my first hypotesis is because of the base capacitance of the BJT. Is it true?

schematic

simulate this circuit – Schematic created using CircuitLab

Best Answer

The question refers to a behaviour of the circuit when simulated in EveryCircuit. A similar behaviour is not observable with other simulators.