UPDATE 1-India's HDFC Bank posts record Q3 profit on steady asset quality

* Q3 net profit 46.43 bln rupees vs 46.31 bln rupees estimate

* Gross NPA ratio 1.29 percent at end-December

* HDFC Bank shares rise 0.5 percent after results (Adds details on results, shares)

Jan 19 (Reuters) - HDFC Bank Ltd reported a record high quarterly profit, as an increase in interest and fee incomes as well as a steady non-performing loan ratio boosted the bottom line for India's second-largest lender by assets.

Net profit for the lender rose 20 percent to 46.43 billion rupees ($728.4 million) for the third quarter ended Dec. 31, from 38.65 billion rupees a year ago.

That was its highest ever quarterly profit and broadly in line with the 46.31 billion rupees analysts had expected on average, according to Thomson Reuters data.

The bank's gross bad loans as a percentage of total loans were 1.29 percent at end-December, versus 1.26 percent at end-September.

HDFC Bank, the most valuable in the sector with a market capitalisation of more than $78 billion, has the lowest bad-loan ratio among India's top lenders as it focuses on retail clients and has relatively smaller exposure to segments such as infrastructure financing.

That has helped it grow loans faster at a time when rivals, especially the state-backed lenders, are struggling with record levels of soured loans in the sector.

HDFC Bank's net interest income rose 24.1 percent from a year to 103.14 billion rupees, helped by average asset growth of 16.6 percent. Its core net interest margin was 4.3 percent. Non-interest income rose 23.1 percent to 38.69 billion rupees.

Shares in HDFC Bank were trading up 0.5 percent by 0656 GMT in a Mumbai market that gained 0.1 percent. ($1 = 63.7425 Indian rupees) (Reporting by Krishna V Kurup in Bengaluru; Editing by Himani Sarkar)