February 3, 2014 - The U.S. Court of Appeals for the Second Circuit ordered the judgments of the district court are affirmed.
June 5, 2013 - The lead plaintiff field a notice of appeal.

May 23, 2013 - The court denied lead plaintiff's motion for reconsideration.

May 6, 2013 - The court granted defendants' motion to dismiss with prejudice.

April 3, 2013 - The lead plaintiff filed a notice of voluntary dismissal of two defendants.

December 21, 2012 - Defendants filed a motion to dismiss.

November 29, 2012 - The lead plaintiff filed an amended complaint.

September 24, 2012 - Lead plaintiff and lead counsel were appointed.

April 30, 2012 - Lead plaintiff motion was filed.

February 29, 2012 - An investor in American Depositary Shares (ADS) of CNOOS Limited (NYSE: CEO) filed a lawsuit in the U.S. District Court for the Southern District of New York against CNOOC Limited over alleged Violations of Federal Securities Laws in connection with certain allegedly false and misleading statements made between January 27, 2011 and September 16, 2011 regarding the Penglai 19-3 oilfield in northern Bohai Bay.

According to the complaint the plaintiff alleges on behalf purchasers of ADS of NYSE: CEO during the period between January 27, 2011 and September 16, 2011, that CNOOC Limited and certain of its officers and directors violated the Securities Exchange Act of 1934. Specifically, the plaintiff alleges that between January 27, 2011 and September 16, 2011 defendants issued allegedly materially false and misleading statements regarding CNOOC Limited’s business and financial results and as a result of those statements, NYSE: CEO ADS traded at artificially inflated prices reaching a high of US$270.64 per ADS on April 4, 2011.

CNOOC Limited reported an increase in its annual Revenue from $14.41billion in 2007 to $29.08billion CNY in 2010 and an increase in its Net Income of $4.96billion in 2007 to $8.64billion in 2010. CNOOC Limited reported that its 6months Revenue in 2011 rose from $6.45billion for the first six months in 2009 to $19.79billion for the first six months in 2011 and its Net Income increased over the same time frames from $1.97billion to $6.25billion.

ADS of CNOOC Limited (NYSE: CEO) rose from as low as $62.32 per share in October ’08 to as high as $265.97 per share on April 8, 2011.

On June 4, 2011 and on June 17, 2011 oil spills occurred at the Penglai 19-3 oilfield in northern Bohai Bay.

The plaintiff alleges that CNOOC Limited and ConocoPhillips China Inc as the operator of the oilfield in northern Bohai Bay failed to disclose the spills when they occurred.

On July 5, 2011, the State Oceanic Administration, China's coastal regulator, officially acknowledged the spills had occurred.

However, the plaintiff alleges that CNOOC Limited downplayed the extent of the damage done by the oil spills and the impact it would have on CNOOC Limited's operations.

On September 2, 2011, the State Oceanic Administration announced that it had ordered CNOOC Limited and ConocoPhillips to immediately suspend all oil production at the Penglai 19-3 oilfield in northern Bohai Bay.

On September 6, 2011, it was announced that CNOOC Limited and ConocoPhillips would establish a Bohai Bay fund to address the environmental impact of the oil spills.

NYSE: CEO ADS fell from over $260 in April 2011 to as low as $152.79 on September 23, 2011.

Since then NYSE: CEO stocks recovered and closed on February 29, 2012 at $226.48 per share.