Berkshire Hathaway’s financial backing was key to saving Constellation Energy, which was faced with the very real possibility of declaring bankruptcy, according to the company’s 170-page proxy statement filed late Friday with the Securities and Exchange Commission.

The bankruptcy of Wall Street investment firm Lehman Brothers on Sept. 15 raised concerns about Constellation’s small connection to the firm. Doubts also arose about the company’s liquidity, sending its stock price plummeting more than 70 percent in three days.