Williams Cos. ( WMB) was soaring in the premarket on a report it was closing in on $2 billion of new financing, including an investment from Warren Buffett. The company also agreed to sell about $1 billion in assets.

Williams has a preliminary agreement with Citigroup ( C) and Buffett's Berkshire Hathaway ( BRK.A) for $2 billion of secured debt, according to the Wall Street Journal.

Williams's stock was soaring 37% to $4.05 in the Instinet premarket.

This is Buffett's second investment in Williams. In March, his MidAmerican Energy acquired Williams's Kern River Gas Transmission Co. for $450 million. It also bought 1.47 million shares of convertible preferred stock for about $275 million. MidAmerican this week agreed to acquire Dynegy's ( DYN) Northern Natural Gas pipeline for $928 million and $950 million in assumed debt.

The Williams investment comes a week after the energy company failed to renew its unsecured bank loans last week, leading to credit downgrades that in turn triggered collateral calls. The company faces $800 million in debt repayments this week.