Laclede Group is planning an offering of up to 9 million shares of its common stock to help fund its pending acquisition of Alabama Gas Corp. The St. Louis-based company also is planning a public offering of $125 million in equity units, with the proceeds also used to fund the cash portion of the Alabama Gas Corp. acquisition. Laclede Group agreed in April to buy Energen Corp.’s Alabama Gas Corp. subsidiary for $1.34 billion in cash. Laclede will assume about $320 million in debt from the Birmingham-based company, Alabama’s largest natural gas utility. The 422,000 customers will increase Laclede’s customer base by 37 percent, to 1.55 million. Last year, Laclede acquired Missouri Gas Energy for $975 million.