  The gravitational waves generated during supermassive black hole (SMBH)
coalescence are prime candidates for detection by the satellite LISA. We use
the extended Press-Schechter formalism combined with empirically motivated
estimates for the SMBH--dark matter halo mass relation and SMBH occupation
fraction to estimate the maximum coalescence rate for major SMBH mergers.
Assuming efficient binary coalescence, and guided by the lowest nuclear black
hole mass inferred in local galactic bulges and nearby low-luminosity active
galactic nuclei (10^5 Msun) we predict approximately 15 detections per year at
a signal to noise greater than five, in each of the inspiral and ringdown
phases. Rare coalescences between SMBHs having masses in excess of 10^7 Msun
will be more readily detected via gravitational waves from the ringdown phase.
