Uncertainty around the succession plans for Yes Bank Ltd's chief executive and exposure to debt-laden Infrastructure Leasing and Financial Services (IL&FS) sent the lender's stock to a four-week low on Friday, a day after it reported a weaker-than-expected quarterly profit.

Yes Bank shares plunged 15 percent to Rs 168.60, while over 93 million shares changed hands, as of 0951 GMT, compared with their 30-day moving average of 64.6 million shares.

The private sector bank posted its first drop in quarterly profit in at least three years on Thursday, as provisions for bad loans and mark-to-market losses more than doubled, and its bad loan ratio widened from the previous quarter.

While asset quality is still a concern, it's the uncertainty around the management and exposure to IL&FS - a major non-banking financial company - that pose a greater risk to Yes Bank, said AK Prabhakar, head of research, IDBI Capital in Mumbai.

IL&FS had defaulted on some of its debt, triggering sharp falls in stock and debt markets in recent weeks and sparking fears about contagion in the country's financial sector. This prompted the government to take control of the company.

Yes Bank said it had a gross exposure of 26.21 billion rupees ($357.29 million) to "an infrastructure and financial services conglomerate", as of September 30, which it described as "entirely standard".

An exposure to IL&FS is still a problem, though the bank stated it was "standard", said AK Prabhakar, adding that "no one really knows" what is going to happen with the ailing IL&FS.

The lacklustre results come as Yes Bank looks for a new chief executive by the February 1 deadline imposed by the Reserve Bank of India (RBI). The RBI had last month denied CEO Rana Kapoor an extension of his term for the second time.

The company's shares have dived up to 47 percent since the RBI trimmed Kapoor's term on September 19.

The bank said on Thursday its search for a successor was still on, and it would take weeks to come to a conclusion.

A pile-up of bad loans have plagued the Indian financial sector and affected the bottomline for many banks as they set aside more money to cover-up for soured assets.

The growth in Yes Bank's loans - 61.2 percent in the quarter - is not sustainable, as the bank is unlikely to be able to raise funds in the current market, Prabhakar added.

Brokerages Slash Target Price

Jefferies cut their target price to Rs 285 from Rs 365 on near-term uncertainty. Jefferies said the appointment of the chief executive officer, new strategy and need for capital could make the stock volatile. The brokerage has maintained their stock rating at "buy".

Citi analysts slashed their target price to Rs 215 from Rs 260, and said the provisions for the quarter were 44 percent higher than they expected.

Yes Bank's provisions, or the amount set aside to cover a future liability, soared 110 percent to 9.40 billion rupees ($128.11 million).

Citi maintained a "neutral" rating on the stock.