Earlier this week, CNOOC Ltd. (NYSE:CEO), China's largest offshore oil and natural gas explorer, announced that it had agreed to pay $15.1 billion in cash to acquire Canada's Nexen Inc. (NYSE:NXY) in the biggest overseas takeover by a Chinese company. The price tag that CNOOC put on Nexen represented a 61 percent premium over the company's stock market value the day before the offer. Nexen's board recommended the deal to its shareholders, but the deal is still subject to regulatory approval.