Goldman Sachs, one of Wall Street’s premier investment banks, was forced to inject $3 billion (£1.5 billion) yesterday into one of its hedge funds after it was hit by a downward spiral in global equities.

The move calls into question for the first time so-called black-box trading, an increasingly prevalent investment strategy on both sides of the Atlantic, whereby hedge fund managers rely on computer models to identify and execute trades.

Goldman Sachs’s announcement came as it emerged that other leading hedge funds had sustained losses of more than 30 per cent, after emergency intervention by central banks in the money markets last week sent share prices plummeting.

Goldman pumped $2 billion into its $3.6 billion Global Equity Opportunities (Geo) fund, topped up with a further $1 billion from investors including Hank Greenberg, the former head of AIG, and the billionaire property entrepreneur Eli Broad. Existing investors in the fund will be able to put in more money on the same terms.

Gary Cohn, the bank’s president and chief operating officer, insisted that the cash injection was not a rescue. “Given the dislocation in the markets, we believe that this is a good investment opportunity for us and the others we’ve brought in,” he said.

The bank has not decided whether to put extra money into its $500 million North American Equity Opportunities fund (Naeo) or its flagship $7 billion Global Alpha fund, both of which have been hit by market turbulence.

Geo lost 32 per cent of its value in the past few weeks, while Global Alpha is down 27 per cent this year. Other funds affected by the downturn in equities included the $29 billion Renaissance Institutional Equities fund, which fell 8.7 per cent this month, and a number of funds at New York’s Tykhe Capital, which sustained losses ranging from 17 per cent to 31 per cent in the month to August 9.

Highbridge Capital Management, the hedge fund manager owned by JPMorgan, saw 18 per cent wiped off the value of its $1.7 billion Highbridge Statistical Opportunities fund in the month to August 8.

The funds use quantitative strategies, which are based on complex computer models with minimum human in-put. The models look for correlations between asset classes but can be thrown by unusually violent market movements.

The type of quant strategy worst affected by the recent turbulence has been equity market neutral (EMN) – a style of investing used by Tykhe, Renaissance and Goldman Sachs, among others.

Goldman Sachs said yesterday that Geo’s performance had “suffered significantly”, while Naeo’s had been “adversely affected” and Global Alpha’s was “disappointing”.

In order to reduce the level of risk posed by Geo and Naeo, both EMN funds, and Global Alpha, a multi-strategy fund, the bank has removed more than 75 per cent of their leveraging. In Geo’s case, this involved paying back about $30 billion to its prime broker, Deutsche Bank.

The $3 billion being injected by new investors will be used to trade the current glut of cheap equities, although it could be used to further delever the fund if the situation in the stock markets worsens.

Goldman is the second investment bank forced to intervene in the activities of its hedge funds. In June Bear Stearns paid $1.6 billion in emergency finance to two of its mortgage-backed securities funds, but was forced last month to obtain bankruptcy protection for the funds, telling investors that they would see little, if any, of their money returned.

Analysts said that Goldman’s move was more positive than that of Bear Stearns, because the bank had the confidence of external investors and financial resources to cover the substantial in-house investment required.