Warren Buffett is reinforcing his 50-year-old relationship with Goldman Sachs after his investment vehicle agreed to become one of the bank’s biggest shareholders by swapping billions of dollars of warrants for shares.

The deal comes as the billionaire is on the hunt for more big acquisitions and is structured in a way that allows his conglomerate Berkshire Hathaway to take a stake in the investment bank without using the $5bn of cash that would be required to exercise the warrants.

The warrants, issued when Mr Buffett rode to Goldman’s rescue in the depths of the financial crisis, gave Berkshire the right to purchase about 9 per cent of the bank for $115 per share before October 1 this year. But in a revised deal announced yesterday, Goldman said it would supply Berkshire with stock equivalent to Mr Buffett’s paper profit on the position.