Igor Sechin spent $55 billion in 2013 to buy competitor TNK-BP and create a Russian oil colossus, pumping about 5 percent of the world’s crude. Almost two years later and investors have written off the deal. Battered by sanctions and oil’s accelerating price crash, OAO Rosneft (ROSN) has lost 38 percent of its market value this year in dollar terms and today the whole company, TNK-BP and all, is worth $50 billion. And buying TNK-BP has left Sechin, Rosneft’s chief executive officer and a long-time ally of Russian President Vladimir Putin , with a lot of debt to repay . State-controlled Rosneft owes about $60 billion to banks and bondholders, making it more indebted relative to earnings than any large oil producer apart from Brazil ’s Petroleo Brasileiro SA. “Their aggressive expansion and debt accumulation made them more vulnerable to the falling oil price and the effect of sanctions,” […]