We report the discovery of a mid-infrared variable AGN which is hosted by an ultraluminous infrared galaxy (ULIRG) candidate in the Sloan Stripe 82 field. textit{WISE} textit{J030654.88+010833.6} is a red, extended galaxy, which we estimate to be at a photometric redshift of 0.28 $leq$ z $leq$ 0.31, based on its optical and near-infrared spectral energy distribution (SED). The factor of two variability over 8 years seen in the textit{WISE} 3.4 and 4.6 $mu$m wavelength channels is not clearly correlated with optical variability in archival data. Based on our estimation of the physical parameters of the host galaxy, textit{J030654.88+010833.6} is possibly a composite AGN/starburst ULIRG in a phase where high star formation $sim$ 70 M$_{odot}$ year$^{-1}$ is occurring. Our estimate of the black hole mass to stellar mass ratio also appears to be consistent with that of broad-line AGN in the local universe. The long-term variability of textit{J030654.88+010833.6} as seen in the textit{WISE} textit{W1} and textit{W2} light curves is likely due to variations in the accretion rate, with the energy being reprocessed by dust in the vicinity of the AGN.
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