Fast spectral variability of gamma-ray burst emission is considered for a number of events seen by the Konus-Wind experiment. The variability manifests itself as a strong correlation between instantaneous energy flux $F$ and peak energy $E_p$. In the ($F,E_p$) plane, the correlation produces distinct tracks in the form of branches and loops representing the different parts of a burst time history. Despite the variety of features seen in different events, the main characteristics of the spectral evolution produce a quite consistent pattern.

3 pages with 2 figures; to appear in the Proceedings of the workshop "Gamma-Ray Bursts in the Afterglow Era: 2nd Workshop", held in Rome, October 17-20, 2000