A handful of senior traders in a Royal Bank of Scotland joint venture are set to share a bonus pool of more than $40 million (£25 million) this year.

Details of the payments are likely to provoke new anger about pay in the financial sector. The Government has been trying desperately to prevent a possible bumper bonus round this year and may use today’s Pre-Budget Report to announce a tax on bonuses.

Shares in RBS fell by 8 per cent to 30.45p yesterday. Rumours swept the market that traders were aggressively short-selling the bank’s stock amid fears of a punitive bonuses tax, which could lead to an exodus of investment bankers from the state-controlled RBS.

Managing directors in RBS Sempra Commodities, which is based in the United States, may receive about $5 million each this year. The majority of its traders are based in Stamford, Connecticut. Last year the business paid out $614 million in staff costs. For the nine months from when it was set up on April 1 until December 31 it made pre-tax profits of $691 million on revenues of $1.4 billion.

Key management at RBS Sempra Commodities shared $46 million in 2008, according to accounts filed at Companies House. The group is thought to include between ten and 20 people out of its 1,000 employees.

RBS Sempra Commodities is among the businesses that the bank must sell as part of its state aid settlement with the European Commission. The Government is particularly keen for RBS to offload the business because of its large exposure to high-risk commodities trading and because of the huge bonuses it paid out last year.

The situation echoes Citigroup’s sale of Phibro, its energy-trading business, to avoid a showdown with the US Government over a proposed $100 million pay package for Andrew Hall, the Phibro chief executive. Citigroup received $45 billion in emergency funding from the US Government to keep it afloat after the credit crunch.

The bonus pool for RBS Sempra Commodities is in addition to the £1 billion pot the Edinburgh-based bank has reserved for bonuses in its main business this year. That pot is at the centre of a heated row between RBS and the Treasury. Some of yesterday’s short-selling was attributed to traders wanting to send a message to the Government that an attack on bonuses would lead to a counter-attack on RBS, in which the Government has invested £45 billion over the past year.

The Sempra bonus pot is separate because the business is a discrete legal entity. Its bonuses are generated on profits made by Sempra. The payout ratio is in line with that of most investment banks with about 50 per cent of revenues going to employees.

RBS Sempra Commodities was created as a joint venture between RBS and Sempra Energy, which is based in California, in April last year. The two divided profits and revenues about equally. It is run from Stamford by Kaushik Amin, a former Lehman Brothers banker who was brought in alongside a handful of senior staff last March when the previous management team quit. His key lieutenant, also based in Stamford, is Satyajit “Satu” Parikh, another former Lehman banker, who is president of the joint venture.

Energy market insiders said that David Messer, the former chief executive, and Frank Gallipoli, the previous president, resigned from Sempra in a disagreement over remuneration.

In February, under pressure from the Treasury, RBS forced most employees in the Sempra joint venture to agree to receive future bonuses in shares rather than in cash and to defer payouts over several years.

RBS is also likely to pay out smaller sums this year, because of Sempra’s slight fall in revenues this year compared with 2008 and to reflect the Government’s crackdown on bonuses. RBS declined to comment.

However, a small number of individuals have contracts entitling them to cash payouts and a straight share of profits.

As well as trading commodities, power and gas, metals and oil markets on behalf of its customers, RBS Sempra takes proprietary positions using the venture’s own money. Energy dealers said that this activity, known as principal trading, accounted for more than half its annual revenues, which are thought to be approaching £900 million for the current year.

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