  We examine the observed diphoton excess at 750 GeV in the framework of
constrained Minimal Supersymmetric Standard Model (cMSSM). The consistency of
cMSSM with the discovery of a 125 GeV Higgs boson and PLANCK/WMAP data for dark
matter relic density (RD) demands large mixing in the scalar top (stop) sector
and consequently, the existence of a light stop quasi-degenerate with the
lightest neutralino. Small decay width due to kinematic and loop suppression of
such a stop allows for the existence of stop-antistop bound states (stoponia).
Identifying the particular part of cMSSM parameter space consistent with Higgs
boson mass as well as RD, we study stoponia as the source of the diphoton
excess.
