HDFC Bank: Did the Merger Create a Bigger Bank—or a Bigger Problem?

Q1 FY27: Advances +15.4% YoY | Deposits +14.7% | NII +6.7% | NIM 3.26% | GNPA 1.17% | Net NPA 0.41% | FY26 RoA ~1.9%

The HDFC Bank That Investors Knew

For years, HDFC Bank was almost boring—and that was a compliment. Strong deposit franchise, high-quality loans, industry-leading asset quality, healthy NIMs, consistent RoA and disciplined growth. Then, on July 1, 2023, HDFC Ltd merged into HDFC Bank. The logic was compelling: a massive mortgage franchise, access to HDFC’s customers, cross-selling opportunities and a much larger balance sheet. Three years later, however, the market’s verdict is less enthusiastic. The problem is increasingly visible in one number: NIM.

The Margin Problem

HDFC Bank’s Q1 FY27 NIM fell to 3.26%, down from 3.38% in the previous quarter and the lowest level reported by the bank. Yet growth has not disappeared: advances grew 15.4% and deposits 14.7%. The problem is that NII grew only 6.7%. The bank is growing faster, but it isn’t monetising that growth as efficiently as it used to.

So What Did the Merger Actually Change?

The merger brought an enormous mortgage book into HDFC Bank. Research at the time estimated mortgage exposure rising from roughly 11% pre-merger to around 31% post-merger. Mortgages are typically lower-yielding than many other retail assets. The combined bank became bigger and more diversified—but also more asset-heavy, lower-yielding and more dependent on improving its funding mix.

The Funding Hangover

HDFC Ltd had historically funded its long-duration mortgage book partly through wholesale borrowings. Those liabilities came into the merged bank. The post-merger Loan-to-Deposit Ratio (LDR) became an important issue, forcing HDFC Bank to focus aggressively on deposits. The resulting cycle was uncomfortable:

need deposits → compete for deposits → pay more for deposits → higher cost of funds → lower NIM.

And CASA Hasn’t Helped Enough

Current Account and Savings Account (CASA) deposits are generally cheaper than term deposits. HDFC Bank’s CASA ratio was around 44% before the merger; by Q1 FY27 it was down to 32.3%. In the latest quarter, total deposits grew 14.7%, but term deposits grew 17.4%, while CASA deposits grew only 9.4%. The bank is growing deposits, but the quality of that growth matters.

The Good News: This Isn’t a Broken Bank

HDFC Bank’s problem is very different from a bank facing asset-quality stress. Q1 FY27 GNPA was 1.17% and Net NPA 0.41%. The bank retains enormous scale, a powerful branch network, strong retail and corporate franchises, healthy capitalisation and a formidable brand. This is not a great bank becoming a bad bank; it is a great bank becoming less efficient during a major structural transition.

What Was the Merger Supposed to Deliver?

The merger was supposed to create synergies, not merely scale. A mortgage customer can potentially become a savings-account, salary-banking, insurance, investment, credit-card and personal-loan customer. HDFC Bank says it has been able to open savings accounts for more than 95% of new-to-bank home-loan customers by disbursement. The opportunity is powerful—but cross-selling takes time while NIM pressure shows up immediately.

This Is the Real Investment Debate

The market does not need HDFC Bank to immediately return to its pre-merger NIM. It needs evidence that the direction has turned. Watch three numbers:

• NIM—can it stabilise and recover?
• CASA—can it move back toward the mid-to-high 30s?
• RoA—can it remain around 1.8–2.0% while the funding mix rebuilds?

FY26 RoA remained around 1.9% despite lower NIMs, helped by cost efficiencies. That is encouraging, but investors should test whether those efficiencies are durable.

So Why Has the Stock Been So Weak?

Investors have lost patience. HDFC Bank has spent years digesting the merger while peers such as ICICI Bank have shown cleaner earnings momentum. The uncomfortable question is: Why own HDFC Bank today when another high-quality private bank is delivering better returns on the same capital? The issue is therefore not simply whether HDFC Bank is a good bank, but whether the opportunity cost of waiting has become too high.

Enter LIC

The Reserve Bank of India approved Life Insurance Corporation of India (LIC) increasing its holding in HDFC Bank from 4.11% to as much as 9.99%. That is significant as a signal of institutional confidence and potentially as a source of incremental demand. But investors should distinguish between a supportive shareholder and a changed business trajectory. LIC’s potential buying can support demand for the stock; it cannot fix NIM, create CASA or improve RoA.

What Could Turn the Story Around?

1. Deposit quality improves: low-cost deposits accelerate without an aggressive deposit-rate war.

2. Legacy borrowings roll off: higher-cost wholesale liabilities are replaced with granular retail funding.

3. Mortgage customers become full banking relationships: account openings translate into active usage, balances, fee income and product penetration.

4. Loan growth becomes more profitable: HDFC Bank does not need maximum growth; it needs profitable growth, with NII and pre-provision operating profit increasingly reflecting balance-sheet growth.

What Could Go Wrong?

If CASA remains stuck, deposit competition stays intense, NIM does not recover, loan growth shifts toward lower-yielding assets, merger synergies take longer, or asset quality deteriorates, HDFC Bank could remain a high-quality but mediocre-returning bank for several more years. The risk is not that HDFC Bank collapses. The risk is that time passes without the economics improving enough.

A Clearer Investor Framework

Buy case: NIM stabilises and recovers, CASA improves, funding costs moderate, NII catches up with advances, RoA remains durable, cross-selling becomes economically visible, and valuation still provides a margin of safety.

Hold/watch case: the franchise remains strong, asset quality is controlled and RoA is stable, but the margin and funding recovery is not yet proven.

Avoid/defer case: NIM and CASA continue deteriorating, deposit costs rise faster than loan yields, NII persistently lags advance growth, RoA weakens, or asset quality begins to deteriorate.

The Metrics That Matter Most

The Road Ahead

HDFC Bank’s problem is not scale. It has plenty. It is not primarily growth either; advances and deposits are growing at healthy double-digit rates. The problem is quality of growth and profitability of that growth. The merger created a much larger mortgage franchise. Now HDFC Bank has to prove that it can turn that franchise into a higher-value banking ecosystem. If it succeeds, today’s weak NIM may eventually be remembered as a temporary cost of integration. If it does not, investors may conclude that the merger created a larger balance sheet without proportionately higher returns.

The Last Word

The HDFC merger gave HDFC Bank scale.

Now the bank has to prove it can turn that scale into returns.

For the next few quarters, watch NIM, CASA and RoA—but read them alongside deposit costs, NII growth, asset quality, cross-selling productivity and valuation.

LIC’s decision to potentially raise its stake to 9.99% is a vote of confidence, but it is not an operating catalyst by itself.

LIC can buy the stock.

Only HDFC Bank can fix the economics.

Sources: HDFC Bank disclosures, Business Standard, Reuters, Nirmal Bang, M