The present invention relates to a wind turbine blade for a rotor of a wind turbine having a substantially horizontal rotor shaft. The blade may comprise a profiled contour comprising a pressure side and a suction side as well as a leading edge and a trailing edge, a chord extending between the leading edge and the trailing edge, and the profiled contour generating a lift when being impacted by an incident airflow. In a cross section of the wind turbine blade perpendicular to a lengthwise direction of the wind turbine blade, a suction side point is defined on the suction side at the trailing edge of the blade, and a pressure side point is defined on the pressure side at the trailing edge of the blade. The suction side point is movable in relation to the pressure side point, and the blade is further provided with a displacement device configured to displace the pressure side point and the suction side point so that a distance between the suction side point and the pressure side point can be varied. The present invention further relates to a wind turbine including such a wind turbine blade and to a method of operating a wind turbine including such a wind turbine blade.