Global business

China's stock markets continued to tumble throughout much of the week. The government introduced more emergency measures, including a six-month ban on selling stakes in companies by large investors, the suspension of IPOs and caps on short-selling. Hundreds of companies suspended trading in their shares. Commodity markets were also affected as worries spread that the authorities were panicking; the Hong Kong and Tokyo markets swooned, too.

Didi Kuaidi, a ride-sharing start-up in China that competes with Uber, was valued at up to $15 billion after a new round of investor fundraising, which saw it raise $2 billion before China's stock markets went into meltdown. Uber also wants to tap Chinese investors, but may find it more difficult now.

Antony Jenkins was sacked with immediate effect as chief executive of Barclays, apparently over frustration among nonexecutive directors at the continuing poor performance of its investment bank. Jenkins had been in the job for three years. John McFarlane, the British bank's new chairman, will take on the chief executive's duties on an interim basis.

BP's share price lost most of the gains it made after the July 2 announcement that it had settled federal, state and local claims for the Deepwater Horizon oil spill in 2010 for $18.7 billion. The larger-than-expected settlement, which will be paid over 18 years, included a record $5.5 billion penalty under the federal Clean Water Act, less than half the maximum fine BP could have incurred. The company's cumulative pretax charge associated with the spill stands at $53.8 billion.

The IMF's annual review of the U.S. economy urged the Federal Reserve to delay an increase in interest rates until the first half of 2016 because of lingering uncertainties about the strength of the recovery. It also warned of the "potential for a rise in global imbalances" if the dollar, which has risen by 20 percent against most big currencies over the past year, were to appreciate more.

Samsung's estimate of its second-quarter earnings disappointed investors. The South Korean firm thinks that profit and revenue will come in lower in the quarter compared with the same three months last year, which suggests that sales of its new Galaxy S6 smartphone have fallen short of expectations.

Microsoft said that it would lay off another 7,800 workers in the smartphone business that it bought from Nokia just last year and booked a $7.6 billion write-down on the business.

Rolls-Royce issued its third profit warning in a year. The company's marine-equipment business has been hurt by the curtailment of exploration projects in the oil industry, and the delivery schedule for its new Trent 7000 aircraft-engine has become snarled in production delays at Airbus, which is mounting the engine on the A330neo. Rolls-Royce issued the profit warning a day after Warren East took the helm as chief executive.

The recent courtships among giant U.S. health insurance companies finally resulted in two of them pairing up, when Aetna offered to buy Humana for $37 billion. Aetna's deal comes two weeks after the Supreme Court upheld tax subsidies that are central to the new health care regime.

IBM showed off prototype computer chips with features just seven nanometers apart (the width of a few strands of DNA), a world first. Though smaller single transistors have been made, the semiconductor industry is fast approaching the limit beyond which smaller transistors will not lead to faster chips. The 7 nm "node" is perhaps the last at which it is economical to try.

Political economy

George Osborne, Britain's chancellor of the exchequer, presented the first budget from a Conservative government free from the constraints imposed by a coalition partner since 1996. As predicted, he announced $18 billion in welfare cuts over time. He also introduced a national "living wage," which will rise to £9 by 2020. Corporation tax will be reduced from 20 to 18 percent.

A court suspended a ballot on the dismissal as honorary chairman of Jean-Marie Le Pen from France's National Front party, which he founded. Le Pen, 87, is feuding with his daughter Marine, who wants to distance the party from its extremist roots.

The U.N. reported that the number of Syrian refugees living in neighboring countries has risen to 4 million, 1 million more than just 10 months ago.