Glo­bal busi­ness

The European Central Bank announced a big program of quantitative easing. The bank said it would purchase $70 billion in assets a month for the next 20 months, including sovereign bonds for the first time. It has come late to QE — other big central banks rolled out their programs years ago — but has been spurred into action by an anemic recovery and "lowflation" in the eurozone.

The Bank of Canada made a surprise move to cut its benchmark interest rate from 1 percent to 0.75 percent. The last cut was in 2009. The central bank said it was responding to "the recent sharp drop in oil prices, which will be negative for growth and underlying inflation."

All nine members of the Bank of England's Monetary Policy Committee have voted to keep interest rates at record lows, according to the minutes from their latest meeting. In previous meetings two members of the MPC, Martin Weale and Ian McCafferty, argued that rates should rise as the economy gathers steam, but they are more concerned now about the prospect of a long bout of very low inflation.

The unexpected decision by Switzerland's central bank to end the Swiss franc's currency ceiling continued to reverberate. Alpari, a foreign-exchange trading firm based in London, declared bankruptcy, and some European banks warned that profits would be hurt. Many homeowners in Poland, Croatia and other countries who have taken out mortgages denominated in Swiss francs counted the cost of soaring repayments.

China's GDP grew by 7.4 percent in 2014, the slowest pace since 1990. After years of hot growth, its leaders seek to chart a course that makes investment less reliant on the credit that has fueled a property boom but also lifts living standards of its burgeoning middle class.

The tumbling price of oil caused more oil companies to curtail their operations. Total, which is based in France, said it would cut spending on production in the North Sea and Canada and accelerate a cost-cutting program; Baker Hughes and Schlumberger became the latest oilfield-services firms to ax jobs; and BHP Billiton said it would reduce the number of rigs it deploys in shale-oil projects.

Travis Kalanick, the boss of Uber, an app-based taxi service, told a conference he wanted a "new partnership" with European regulators after months of lawsuits. Adopting a conciliatory tone, Kalanick recognized a new legal framework is needed to cope with the growth of taxi apps.

Po­lit­i­cal ec­on­omy

Chad sent 2,000 troops to Cameroon to help fight jihadists from Boko Haram, a group based in northeastern Nigeria that has slaughtered thousands of people there and stepped up its raids across the Cameroonian border. Paul Biya, the president of Cameroon, described Boko Haram as a "global threat" as he appealed for international help.

At least 43 churches were burned in Niamey, the capital of Niger, as protests against the publication of satirical images of Muhammad in Charlie Hebdo turned violent. The global solidarity shown toward the French magazine after 10 of its journalists were killed by Islamists has not been shared by everyone. Protests also took place in Pakistan, Algeria and other countries; 800,000 attended a rally in Grozny, the capital of Chechnya, a Russian republic with a Muslim majority.

In Yemen, Houthi rebels aligned with Iran strengthened their hand in Sanaa, the capital, when they seized the presidential palace after a gunfight. They issued a number of constitutional demands to increase their power but subsequently promised to pull back their forces in exchange for concessions.

Prominent figures involved in a prodemocracy campaign in Hong Kong complied with summonses to report to the police. They included Joshua Wong, a student leader, and Jimmy Lai, a wealthy publisher. Both were arrested on their arrival but released after being questioned.

Four district officials in Shanghai were dismissed for their alleged failings in connection with a stampede on New Year's Eve that killed 36 people on the city's riverfront. A deputy mayor of Shanghai said the incident had been "totally avoidable." The authorities have kept close watch on families of the victims, apparently in order to limit their contacts with journalists.