The offer came after OCBC reached a deal with members of Wing Hang's founding Fung family, their affiliates and related family trusts, as well as BNY International Financing Corp, to buy a nearly 45 percent stake in the bank.
The Singapore lender has also reached separate deals with other shareholders that would increase its stake to 50.66 percent.
OCBC is offering HK$125 a share to buy all the stock of Wing Hang, according to a joint announcement on Tuesday. The $4.95 billion offer is lower than expectations, with sources previously estimating the deal could be worth $5.3 billion.
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Wing Hang and OCBC had been locked in exclusive negotiations since December after several players, including Singapore's United Overseas Bank, walked away from the deal on price concerns, sources had told Reuters earlier.
"It is slightly lower than my original expectation of at least HK$130, but I suppose it's fair from OCBC's standpoint because they don't need revenue or cost synergy for the deal," said Steven Chan, an analyst at Maybank Kim Eng who covers Hong Kong and Chinese banks.
"The return on investment should be roughly equal to the cost of funding if they are going to finance the deal half by debt and half by equity." The offer price translates to a book value of 1.77 times for Wing Hang, according to an OCBC statement.
A Barclays note said that after adjustment of a 2013 final dividend payment totaling HK$498 million and premises revaluation reserve of HK$2.1 billion, the price-to-book would be 2.02 times.
Yue Xiu Group, the trading arm of China's Guangzhou city government, paid a multiple of 2.08 times to buy Hong Kong's Chong Hing Bank last year.
OCBC has received in-principle approval for the purchase from Hong Kong and Singapore regulators, with formal approval needed by June 30 for the deal to go through. The acquisition is not subject to the approval of its shareholders.
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OCBC has received in-principle approval for the purchase from Hong Kong regulators, with formal approval needed by June 30 for the deal to go through.
The deal has the approval of Singapore regulators. The acquisition is not subject to the approval of its shareholders.
OCBC is being advised by Bank of America, and Wing Hang by Goldman Sachs, Nomura Holdings and KPMG.