Natural gas producer EQT (EQT -8.44%) has a deal in place to buy pipeline operator Equitrans Midstream (ETRN 1.84%) for $5.5 billion, bringing a former subsidiary back in-house. Investors reacted by sending shares of EQT down about 7% as of 10:18 a.m. ET.A "transformational" acquisitionEQT is a natural gas production company focused on the Appalachian Basin, including the Marcellus shale basin. In 2018, the company spun its pipeline operations out as an independent business under the watchful eye of activis ...