Lloyds blamed the mistake on the mayhem that followed Kleinwort Benson's last-minute decision to cut the price of the offer for a second time to ensure the float did not fail.
Thousands of private investors were posted application forms asking them to re-confirm their interest in buying the shares at the lower price and had just six days to reply. However, it is understood that hundreds of shareholders missed out. Some were away on holiday while others claim they never received the letters.
The mix-up affected around 100 investors at share shop Hargreaves Landsdown Asset Management while another share shop, Dealwise also blamed Lloyds.
Lloyds said it would compensate investors who were affected, at a cost of around pounds 10,000.