Quantum oscillations reveal sixfold fermions in cubic <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>β</mml:mi> <mml:mtext>−</mml:mtext> <mml:msub> <mml:mi>PtBi</mml:mi> <mml:mn>2</mml:mn> </mml:msub> </mml:mrow> </mml:m

High-resolution de Haas---van Alphen measurements on cubic \ensuremath{\beta}-PtBi${}_{2}$, combined with fully relativistic density functional calculations, reveal quantum oscillations arising from a symmetry-enforced sixfold band touching at the Brillouin zone corner. Three small electron pockets derived from this degeneracy, lying ~25 meV below the Fermi level, are identified through their low oscillation frequencies and angular dependence. These results provide bulk evidence for sixfold fermions in \ensuremath{\beta}-PtBi${}_{2}$, bridging ARPES observations and theory and establishing a robust platform for multifold quasiparticles.