Southwest Gas (NYSE:SWX – Get Free Report) and AltaGas (OTCMKTS:ATGFF – Get Free Report) are both utilities companies, but which is the better stock? Get Southwest Gas alerts:Insider and Institutional Ownership92.8% of Southwest Gas shares are held by institutional investors. ProfitabilityNet Margins Return on Equity Return on Assets Southwest Gas 19.95% 6.95% 2.58% AltaGas N/A N/A N/AValuation and EarningsThis table compares Southwest Gas and AltaGas’ net margins, return on equity and return on assets. Given Southwest Gas’ stronger consensus rating and higher possible upside, equities analysts plainly believe Southwest Gas is more favorable than AltaGas. The Midstream segment engages in the natural gas gathering, processing, and extraction with 1.2 billion cubic feet per day (Bcf/d) of extraction processing capacity and approximately 1.2 Bcf/d of raw field gas processing capacity; fractionation and liquids handling business; and natural gas and natural gas liquids marketing activities.