MidAmerican Energy’s acquisition of a Maryland-based company is one step closer to completion. In September, Des Moines-based MidAmerican Energy announced its intentions to buy Constellation Energy Group for more than four-and-a-half billion dollars.

Today, the Federal Energy Regulatory Commission waived a manditory waiting period, giving the companies the go-ahead to pursue the deal. There are other regulatory hurdles, but executives of the companies expect MidAmerican will close the deal in nine to 12 months.

Constellation is the nation’s largest wholesale power seller and it’s the country’s number one supplier of electricity to business and industry. MidAmerican currently provides electricity and natural gas to nearly seven million customers worldwide, including over 600-thousand in Iowa. While MidAmerican Holdings Company is headquartered in Des Moines, it is part of Warren Buffett’s Berkshire Hathaway empire.