Even though they are among the riskiest stocks on the market, investing in some penny stocks can mean a lot of profits. In times of economic uncertainty, penny stock investment can be a lifesaver for investors. In this article, you’ll learn more about three of the most promising penny stocks to buy on the market and what makes them fantastic portfolio additions going into the second half of the year. Let’s dive right in.Ardelyx (ARDX)Source: MacroEcon / Shutterstock.comArdelyx (NASDAQ:ARDX) is a biopharmace ...