Lloyd's is expected to lose £5bn in the 2000 and 2001 years of account, according to ratings agency Moody's.
Its loss predictions for those years are £2.4bn and £2.6bn respectively. These are £430m and £875m higher than Lloyd's own estimates.
But the rating agency predicted there was "genuine potential" for a profit of more than £1bn for 2002, assuming that it was a "normal loss" year.
Moody's senior analyst Dominic Simpson said: "Moody's currently expects around 80% and 70% of syndicates underwriting in 2000 and 2001 respectively to be loss-making. In addition, we also forecast losses for each of the main Lloyd's sectors in both years, with the exception of motor, which is expected to be profitable in 2001."
Although 1999 represented the bottom of the most recent down cycle, the forecast losses for 2000 and 2001 were larger due to the impact of the World Trade Centre disaster, Moody's said.
Moody's assessment of Lloyd's is based on public information only.