PetroChina Company, Limited () ( )'s a Chinese oil company and's the listed arm of state-owned China National Petroleum Corporation (CNPC), mainland China's biggest producer of oil. and following its debut on the Shanghai index, its market value tripled. PetroChina overnight became the first company with a trillion dollar market cap. Similarly, a century earlier, U.S. Steel was the first company with a billion dollar market cap. History PetroChina was established as a joint stock company with… (More on Petrochina)