National Australia Bank is the latest to join the swelling ranks of lenders offering residential mortgages at under rates under 3 per cent.In a notification to mortgage brokers on Monday, NAB said it would begin marketing a 2 year fixed rate home loan priced at 2.88 per cent from this morning. The repricing represents a 21 basis point reduction in the two year fixed product and trumps ANZ's 2.98 per cent and CBA's 2.99 per cent.NAB said in the note to brokers that the new pricing was only available to first home buyers who were owner occupiers.The loan is also only available on principal and interest repayment terms for borrowing  above A$150,000.NAB told brokers that loan applications would be automatically approved subject to loan applicants meeting a maximum 90 per cent loan-to-value ratio requirement.The major banks' advertised pricings in the fixed rate market are among the sharpest available.According to Canstar, other lenders offering two year fixed rates under 3 per cent  include Adelaide Bank, Mortgage House, Pacific Mortgage Group, IMB Bank and Newcastle and Permanent Building Society."There are now more than 150 different mortgage products in the variable and fixed rate segments of the market that are priced below three percent," said Canstar director Steve Mickenbecker."The risk that borrowers have to weigh is whether variable rates will continue to reduce over the next few years."A slew of non-bank lenders already market standard variable rate mortgages at a discount to NAB's two year rate.They include Athena Home Loans(2.84 per cent), Homestar (2.74 per cent) and Freedom Lend (2.79 per cent).