Iowa’s largest utility is about to get a lot bigger. MidAmerican Energy is buying Constellation Energy, which was one casualty in this wild week on Wall Street. The Des Moines-based MidAmerican serves some 720,000 gas and electric customers in Iowa, Illinois, Nebraska and South Dakota.

Baltimore, Maryland-based Constellation operates in seven states, primarily on both coasts. MidAmerican is under the umbrella of Omaha-based Berkshire-Hathaway, headed by billionaire Warren Buffett. The buyout, pending stockholders’ and regulators’ approval, is worth four-point-seven billion dollars.