  We present results from three weeks' photometric monitoring of the magnetic
helium-strong star sigma Ori E using the MOST microsatellite. The star's light
curve is dominated by twice-per-rotation eclipse-like dimmings arising when
magnetospheric clouds transit across and occult the stellar disk. However, no
evidence is found for any abrupt centrifugal breakout of plasma from the
magnetosphere, either in the residual flux or in the depths of the light
minima. Motivated by this finding we compare the observationally inferred
magnetospheric mass against that predicted by a breakout analysis. The large
discrepancy between the values leads us to argue that centrifugal breakout does
not play a significant role in establishing the magnetospheric mass budget of
sigma Ori E.
