Shares of Oversea-Chinese Banking Corp rose slightly in early trading on Tuesday after Singapore's second-biggest lender made a formal offer to buy Hong Kong's Wing Hang Bank for HK$38.428 billion ($6.2 billion).

OCBC shares gained 0.3% to $9.54 after its trading halt was lifted. Singapore's broader Straits Times Index was 0.4% higher.

OCBC is offering HK$125 a share to buy all shares of Wing Hang, according to a joint announcement, after having reached a deal with the bank's biggest shareholder to purchase a nearly 45% stake.