 Merrimack Pharmaceuticals NASDAQ:MACK and Ardelyx NASDAQ:ARDX are both small-cap medical companies, but which is the better business? We will contrast the two companies based on the strength of their profitability, valuation, analyst recommendations, risk, earnings, dividends and institutional ownership. Profitability This table compares Merrimack Pharmaceuticals and Ardelyxs net margins, return on equity and return on ... 