SEC scrutinises 'bets against the market'

The US markets regulator is investigating possible insider trading in the run-up to last month's historic cut in the rating of the government's long-term debt.

The Securities and Exchange Commission is reported to have issued subpoenas demanding extra information about specific trades made soon before Standard & Poor's downgraded the country's rating by one notch to AA-plus on 5 August.

The SEC has directed its inquiry at firms that bet the stock market would fall. The downgrade sent US shares down 5.6 per cent the day after the announcement.

The SEC has been inspecting S&P's methods in making the downgrade and whether the firm followed its own procedures for keeping the decision secret.