Why is HDFC falling?

I don't think there's any fundamental issue with the bank. Note that Kotak has also fallen so it's not only HDFC Bank.

Issues regarding their merger with parent company HDFC have led to some institutional selling. SBI and Nippon MFs sold around 50L of the bank's shares.

This has happened before too with HDFC AMC and Zomato as well, the point is these negative sentiments are opportunities to downward average, especially for a fundamental investor.

Because they've still not moved on from the strategy of CALLING people at odd times everyday to offer "credit cards" and "personal loans" /s

Poor digital play and they need to modernize fast

There was a good article on FinShots on HDFC - it has mentioned a couple of compelling reasons

I read their NIM - Net Interest Margin fell to 3.5% vs the usual 4-4.2%. Hence the crash.

It will likely recover soon and lead the banking rally imo,

Disclaimer: 13% of my personal portfolio is on HDFC

There's a sell off triggered by norms changes in the kyc of fpis. Post March it's going to be harder for fpis to park their money through shell companies. Source: investment advisors

Because someone big is selling