Global business

A judge ruled that the American government exceeded its authority when it sequestered AIG's equity in return for a bailout following the collapse of Lehman Brothers in 2008. Hank Greenberg, a former chief executive and chairman of AIG, brought the case on behalf of shareholders seeking $40 billion in damages; the court's decision surprised observers who thought his lawsuit was a long shot. But the judge also reasoned that if the government had not rescued AIG its investors would have been wiped out during Wall Street's meltdown, so he awarded no compensation. Greenberg is to appeal against that part of the ruling.

Dick Costolo took markets by surprise when he announced that he was stepping down as Twitter's chief executive. The social media company has been struggling to increase its number of users at a rate to satisfy investors; a disappointing quarterly earnings report in April caused its share price to plunge by 20 percent within minutes. Costolo's interim replacement is Jack Dorsey, one of Twitter's founders.

The board at 21st Century Fox approved leadership changes at the film and television giant that will see Rupert Murdoch hand over the reins as chief executive to his younger son, James, on July 1. Rupert Murdoch will share the job he currently holds of executive chairman with his eldest son, Lachlan.

The European Court of Justice found that the "outright monetary transactions" program, introduced by the European Central Bank in 2012 as part of its promise to do "whatever it takes" to prop up the eurozone, is legal. The decision makes it easier for the ECB to intervene should the Greek crisis escalate. Under OMT the bank can buy bonds on secondary markets in unlimited quantities, but opponents of the plan, notably in Germany, claim this is outside its remit.

Russia's central bank reduced its main interest rate by one percentage point, to 11.5 percent, the fourth cut this year. Some expected a bigger reduction, but the Bank of Russia stressed that inflation, which has slowed to 15.8 percent, could pick up again, limiting the scope for more easing.

Colt, a gunmaker that made its name with the first mass-produced revolvers in the 19th century, filed for bankruptcy protection. The company still makes weapons for America's armed forces, but it lost a big contract in 2013 and has since piled up debts. After it restructures, Colt insists, it will be back with a bang.

Political economy

After another round of failed talks between Greece and its creditors, Alexis Tsipras, the Greek prime minister, hurled abuse at them, accusing the IMF of "criminal responsibility." Coming just before two crunch dates for debt repayments to the IMF and the European Central Bank, such language raised new fears of a Greek exit from the euro. Finance ministers gathered in Luxembourg for the first of what may be a series of crisis negotiations.

A few days after America said it was considering putting heavy weapons in Poland and the Baltic states, Russia's Vladimir Putin announced that his government would add 40 new nuclear missiles to its stockpile this year.

Ahead of a planned visit to the Americas, the pope published an encyclical on the environment in which he warned of the catastrophic risks from man-made climate change and called on policymakers to do more to avert it.

Hong Kong's legislature rejected a proposal backed by China's leadership for the introduction of universal suffrage in choosing the territory's chief executive. Pro- democracy politicians denounced the offer as a sham, saying mechanisms would remain in place to ensure no critic of the Communist Party would be elected. Before the vote prodemocracy campaigners protested outside the legislature, though many members of the public think the proposal, though flawed, should be accepted.

Australia and China signed a free-trade deal, abolishing many tariffs. The Australian prime minister, Tony Abbott, called it a "momentous" occasion for the two countries. The deal includes the abolition of most tariffs on China's imports of natural resources and manufactured goods from Australia.

Suicide-bombers attacked the capital of Chad in what appears to be retaliation by Boko Haram, a jihadist outfit, for Chad's military intervention against the group in Nigeria. Reports said that 23 people as well as four suicide-bombers were killed in the blasts.