Twitter and Amex, I hope, have thought through the consequences and have limited the launch to a dozen or so big brands such as Best Buy, Virgin America, Sports Authority and Whole Foods.

FORBES: Amex and Twitter Nail Social Commerce

This means that more efficient banks will inevitably get a bigger share of the cake in concentrated markets, such as Britain, and buy weaker, less efficient competitors in fragmented markets such as America.

ECONOMIST: Winners and losers

In the news lately, Priceline was offering abnormally conservative third quarter guidance despite being a favorite pick by firms such as Bank of America, which downgraded the company from Buy to Neutral on August 8.

FORBES: Priceline Customers: Bring Back the Negotiator!

Some people avoid supermarkets and buy their groceries online from firms such as Fresh Direct in America and Ocado in Britain.

ECONOMIST: Competition in your local supermarket is getting vicious

Mr Vasella claims that big buyers, such as Wal-Mart in America and health-care providers in emerging markets, want to be able to buy a full range of patented and generic products from one supplier.

ECONOMIST: The best medicine? | The

Spending in rich countries, such as America and Britain, will flounder as long as households look to pay down the debts they acquired to buy expensive homes.

ECONOMIST: Economics focus