Many of London's currency dealers have retooled themselves to trade more sophisticated products, such as interest-rate swaps and forward rate agreements.

ECONOMIST: Derivatives and foreign exchange

Since the income from the projects is not dependent on interest rates, the company entered into interest rate swap agreements which act as hedges.

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Interest-rate swap agreements are essentially financial bets many states and cities made in recent years in the hope of protecting themselves from higher rates.

WSJ: Detroit's Decline Adds to Financial Strains

It is not hard to conjure up a scenario where agreements on, say, tax harmonisation or exchange-rate policy within the euro group start raising questions about the full access of non-euro members to the single market.

ECONOMIST: Euro-apartheid?

Another tactic: locking in prices with tailored multiyear agreements with formulas governing whether clients grant or refuse a requested rate increase.

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The draft legislation comes after months of debate and failed proposals, including retroactive cuts to investment agreements, a full halt in new subsidies for renewable energy projects and a variable tax rate on energy production that sank under pressure from wind and solar sectors already struggling to survive.

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Mr Alexander added that the government, together with Germany and France, was putting additional funds into the Organisation for Economic Co-operation and Development, to aid work on establishing global agreements to prevent companies avoiding tax by moving profits from one country to another with a lower tax rate.

BBC: Tax not 'voluntary', Alexander tells firms