  We estimate the two-point correlation function in redshift space of the
recently compiled HIPASS neutral hydrogen (HI) sources catalogue, which if
modeled as a power law, $\xi(r)=(r_{0}/r)^{\gamma}$, the best-fitting
parameters for the HI selected galaxies are found to be $r_{0}=3.3 \pm 0.3
h^{-1}$ Mpc with $\gamma=1.38 \pm 0.24$. Fixing the slope to its universal
value $\gamma=1.8$, we obtain $r_{0}= 3.2\pm 0.2 h^{-1}$ Mpc. Comparing the
measured two point correlation function with the predictions of the concordance
cosmological model, we find that at the present epoch the HI selected galaxies
are anti-biased with respect to the underlying matter fluctuation field with
their bias value being $b_{0}\simeq 0.68$. Furthermore, dividing the HI
galaxies into two richness subsamples we find that the low mass HI galaxies
have a very low present bias factor ($b_{0}\simeq 0.48$), while the high mass
HI galaxies trace the underlying matter distribution as the optical galaxies
($b_{0}\simeq 1$). Using our derived present-day HI galaxy bias we estimate
their redshift space distortion parameter, and correct accordingly the
correlation function for peculiar motions. The resulting real-space correlation
length is $r^{\rm re}_{0}=1.8 \pm 0.2 h^{-1}$Mpc and $r^{\rm re}_{0}=3.9 \pm
0.6 h^{-1}$Mpc for the low and high mass HI galaxies, respectively. The
low-mass HI galaxies appear to have the lowest correlation length among all
extragalactic populations studied to-date. Also, we have correlated the
IRAS-PSCz reconstructed density field, smoothed over scales of 5$h^{-1}$ Mpc,
with the positions of the HI galaxies, to find that indeed the HI galaxies are
typically found in negative overdensity regions ($\delta\rho/\rho_{\rm PSCz}
\mincir 0$).
