AbstractA high level of stellar activity in the form of frequent flaring and frequent mass ejections can lead to the total loss of exoplanetary atmospheres due to evaporation and erosion. Simulations have shown such scenarii for close-in exoplanets orbiting M-stars. Information on stellar flaring activity is accessible more easily than information on stellar mass ejections, simply due to the difference in detection. In the National Aeronautics and Space Administration/Far Ultraviolet Spectroscopic Explorer spectra of the dM star AD Leonis we find an interesting event lasting for only one spectrum. The first component of the OVI (103.19 nm, 103.76 nm) duplet shows an enhancement of the blue wing, shifted by about 90 km s⁻¹. This event occurred one spectrum after a flare. We discuss several solar/stellar phenomena that might produce such a spectral feature and could therefore explain this event.