William Durant, the founder of General Motors, lost control of his company due to his aggressive expansion plans. Going wholeheartedly from a carriage manufacturer to an automotive force, Durant used debt to finance his takeovers and mergers with other auto startups. The bankers, who helped with refinancing efforts, and the stockholders, to whom Durant had sold and resold shares, finally decided to oust him and consolidate current holdings, rather than to continue the breakneck expansion.

Durant immediately began to look for a way to regain control of his company. He hooked up with a Swiss racer named Louis Chevrolet and the two formed Chevrolet. Although Durant soon disagreed with Chevrolet about the direction of the company and bought him out, the company was highly successful. Durant still held a large amount of GM stock and he used the profits from his new company to buy even more.

Durant eventually owned enough GM stock to bring the company to the table for merger/buyout talks. Durant offered a five-for-one stock swap. GM shareholders jumped at the chance to get another popular brand under their umbrella at a cheap price. GM particularly relished merging with a brand that could help it fight off Ford. As part of the deal, Durant regained control of the company he had founded.

However, Durant's success was not long-lived. The company once again suffered from Durant's management and in 1920 Pierre Du Pont, Durant's main financer, ousted him for good. Durant tried repeatedly to replicate his former successes, but he was never able to create another GM or Chevy.

(For related reading, see Henry Ford: Industry Mogul And Industrial Innovator.)

This question was answered by Andrew Beattie.