China is said to have told some brokerage firms to reduce proprietary trading in the foreign-exchange market, as authorities step up their defense of the beleaguered currency. The People’s Bank of China asked several brokers earlier this week to reduce proprietary desk trading of their FX positions, without giving specific guidance on the limit of trading volume, according to people with knowledge of the matter. Some of these firms have almost halted proprietary trading since then, the people said, declining to be named discussing private matters. The central bank didn’t immediately reply to a fax Bloomberg sent ... (full story)