New Delhi: It has not been a very smooth ride for private sector lenders in the banking history of India with the latest case of Yes Bank falling into the RBI's interim management before a bigger sovereign structure is worked under the central bank's supervision.Poor corporate governance and NPAs have been their Achilles' heel.Way back in 2004, the crisis-ridden Global Trust Bank was merged with the Oriental Bank of Commerce by the Reserve Bank of India. since 2001, the GTB's name was associated with scams and controversies, thereby casting shadows over the credibility of the bank and its management.Due to the over exposure to capital markets and huge NPAs, the bank was in a financial mess. When the GTB tried to cover up its monumental NPAs through under provisioning, the RBI - the central bank and the regulatory authority for banks in India, appointed an independent team to review the finances of the bank and this revealed various financial discrepancies kept covered by the bank.The RBI had imposed a three month moratorium on GTB on the ground of "wrong financial disclosures" and within two days, the bank was merged with the public sector OBC and lost its separate identity.On GTB issues, former RBI Governor Y.V. Reddy wrote in his memoirs "Advice & Dissent": "Soon after I joined as Governor in September 2003, I had to take a view on cleaning up GTB."GTB continued to be on the list of problem banks. We sounded leading private sector banks if they could take over GTB. Surprisingly, they did not evince interest. We decided to act before it is too late."In yet another banking crisis, HDFC Bank had taken over the Centurion Bank of Punjab (CBoP) in an all-stock deal. HDFC Bank board, in 2008, approved the acquisition for Rs 9,510 crore in one of the largest mergers in the financial sector in India. CBoP shareholders got one share of HDFC Bank for every 29 shares held by them.This was HDFC Bank's second acquisition after Times Bank and it strengthened HDFC Bank's distribution network in the northern and the southern regions. The entire process of the merger took four months for completion.In the merged entity, Rana Talwar's Sabre Capital held less than 1 per cent stake against 3.48 in CBoP.In the recent times, there was the PMC Bank crisis.The RBI had superseded the board of crisis-hit Punjab and Maharashtra Cooperative Bank Ltd, Mumbai and appointed Jai Bhagwan Bhoria as its new administrator.The alleged irregularities in the bank came to the fore when the RBI restrained the bank from doing business activities for six months and capped the withdrawal by the depositors at Rs 1,000 a day which subsequently increased to Rs 50,000. It sent shockwaves through the banking sector as the bank was catering to small depositors, and the curbs imposed by the RBI stoked the apprehension of another major scam in the country's banking sector.Apart from institutions such as IDBI, ICICI, HDFC and UTI, the Centurion Bank, Bank of Punjab, Times Bank, Global Trust Bank and IndusInd Bank of the Hindujas were given licenses as private banks . Barring IndusInd, all the others have been merged into another bank.