The mortgage, which was launched on 1 September, prompted a huge increase in consumer interest in HSBC mortgages. The deal has led to a total of £245 million of discount mortgages having been sold during September alone.
Martijn van der Heijden, head of mortgages at HSBC, said: "Our range of mortgages have topped the best buy tables for most of the year. We made a commitment to stay open for business and extending the 1.99% mortgage is part of that."
Last week HSBC announced that is making an additional half a billion pounds of mortgage funding available to home buyers with deposits of just 10%. The bank has now reached the £1 billion it committed to lending earlier this year, meaning HSBC will now make £1.5 billion available to home buyers requiring 90% loan to value in 2009.