  We investigate logarithmic price returns cross-correlations at different time
horizons for a set of 25 liquid cryptocurrencies traded on the FTX digital
currency exchange. We study how the structure of the Minimum Spanning Tree
(MST) and the Triangulated Maximally Filtered Graph (TMFG) evolve from high (15
s) to low (1 day) frequency time resolutions. For each horizon, we test the
stability, statistical significance and economic meaningfulness of the
networks. Results give a deep insight into the evolutionary process of the time
dependent hierarchical organization of the system under analysis. A decrease in
correlation between pairs of cryptocurrencies is observed for finer time
sampling resolutions. A growing structure emerges for coarser ones,
highlighting multiple changes in the hierarchical reference role played by
mainstream cryptocurrencies. This effect is studied both in its pairwise
realizations and intra-sector ones.
