Under ambient conditions, pure antimony pentafluoride (SbF5) is a strongly associated liquid. Early NMR works established that the molecules oligomerize via cis-fluorine chains. We have employed ab initio molecular dynamics to investigate the structure of liquid SbF5. The simulation confirms the strong tendency of molecules to oligomerize via a barrierless, diffusion-limited process. The nature of the SbF5 chemical bond and the experimentally observed propensity to form cis-fluorine chains has been analyzed in terms of Wannier localized orbital functions. The calculation indicated a very strong ionic character for the Sb-F bond.