The ultrafast-rotating ( P _ { \mathrm { rot } } \approx 0.44 d ) fully convective single M4 dwarf V374 Peg is a well-known laboratory for studying intense stellar activity in a stable magnetic topology .
As an observable proxy for the stellar magnetic field , we study the stability of the light curve , and thus the spot configuration .
We also measure the occurrence rate of flares and coronal mass ejections ( CMEs ) .
We analyse spectroscopic observations , BV ( RI ) _ { C } photometry covering 5 years , and additional R _ { C } photometry that expands the temporal base over 16 years .
The light curve suggests an almost rigid-body rotation , and a spot configuration that is stable over about 16 years , confirming the previous indications of a very stable magnetic field .
We observed small changes on a nightly timescale , and frequent flaring , including a possible sympathetic flare .
The strongest flares seem to be more concentrated around the phase where the light curve indicates a smaller active region .
Spectral data suggest a complex CME with falling-back and re-ejected material , with a maximal projected velocity of \approx 675 km s ^ { -1 } .
We observed a CME rate much lower than expected from extrapolations of the solar flare–CME relation to active stars .