  This paper investigates the clustering properties of SCUBA-selected galaxies
in the framework of a unifying scheme relating the formation of QSOs and
spheroids (Granato et al. 2000). The theoretical angular correlation function
is derived for different bias functions, corresponding to different values of
the ratio $M_{\rm halo}/M_{\rm sph}$ between the mass of the dark halo and the
final mass in stars. SCUBA sources are predicted to be strongly clustered, with
a clustering strength increasing with mass. We show that the model accounts for
the clustering of Lyman-break Galaxies, seen as the optical counterpart of low-
to intermediate-mass primeval spheroidal galaxies and is also consistent with
the observed angular correlation function of Extremely Red Objects. Best
agreement is obtained for $M_{\rm halo}/M_{\rm sph}=100$. We also consider the
implications for small scale fluctuations observed at sub-mm wavelengths by
current or forthcoming experiments aimed at mapping the Cosmic Microwave
Background (CMB). The predicted amplitude of the clustering signal in the 350
GHz channel of the Planck mission strongly depends on the halo-to-bulge mass
ratio and may be of comparable amplitude to primary CMB anisotropies for
multipole numbers $l\simgt 50$.
