The Chinese state-controlled company that acquired Calgary-based Nexen in a landmark $15.1-billion takeover, CNOOC Ltd., began trading on Canada's largest stock market Wednesday.

CNOOC's share-substitutes, known as American depository receipts, have the symbol CEO on the Toronto Stock Exchange. Each ADR is the equivalent of 100 common shares of CNOOC Ltd., which has its primary listing in Hong Kong.

"Canada became an important investment destination for CNOOC Limited following our acquisition of Nexen," Li Fanrong, CNOOC's chief executive, said in a statement Wednesday.

"Listing on the TSX represents our continuous commitment to maintaining transparency and good corporate governance in the countries where we operate."

No new equity is being issued but the listing but gives Canadians insight into CNOOC's market value.

The ADRs rose $4.31 to $210.87 on Wednesday at the Toronto Stock Exchange. The same type of instrument listed on the New York Stock Exchange were worth $205.81 US at the time.

The TSX listing was part of CNOOC's commitments to win approval for the takeover from the Canadian government.

The Harper government approved the CNOOC-Nexen deal in December under existing foreign-takeover rules but also announced that future deals by state-owned enterprises would face greater scrutiny.