  Eddington outflows probably regulate the growth of supermassive black holes
(SMBH) in AGN. I show that effect of the Rayleigh--Taylor instability on these
outflows means that SMBH masses are likely to be a factor of a few below the $M
- \sigma$ relation in AGN. This agrees with the suggestion by Batcheldor (2010)
that the $M - \sigma$ relation defines an upper limit to the black hole mass. I
further argue that observed AGN black holes must spend much of their lives
accreting at the Eddington rate. This is already suggested by the low observed
AGN fraction amongst all galaxies despite the need to grow to the masses
required by the Soltan relation, and is reinforced by the suggested low SMBH
masses. Most importantly, this is the simplest explanation of the recent
discovery by Tombesi et al (2010a, b) of the widespread incidence of massive
ultrafast X--ray outflows in a large sample of AGN.
