  We report magnetic field dependent transport measurements on a single crystal
of cubic YSb together with first principles calculations of its electronic
structure. The transverse magnetoresistance does not saturate up to 9 T and
attains a value of 75,000 % at 1.8 K. The Hall coefficient is electron-like at
high temperature, changes sign to hole-like between 110 and 50 K, and again
becomes electron-like below 50 K. First principles calculations show that YSb
is a compensated semimetal with a qualitatively similar electronic structure to
that of isostructural LaSb and LaBi, but with larger Fermi surface volume. The
measured electron carrier density and Hall mobility calculated at 1.8 K, based
on a single band approximation, are 6.5$\times10^{20}/$cm$^{3}$ and
6.2$\times10^{4}$cm$^{2}$/Vs, respectively. These values are comparable with
those reported for LaBi and LaSb. Like LaBi and LaSb, YSb undergoes a magnetic
field-induced metal-insulator-like transition below a characteristic
temperature T$_{m}$, with resistivity saturation below 13 K. Thickness
dependent electrical resistance measurements show a deviation of the resistance
behavior from that expected for a normal metal; however, they do not
unambiguously establish surface conduction as the mechanism for the resistivity
plateau.
