Investors interested in stocks from the Medical - Biomedical and Genetics sector have probably already heard of Vertex Pharmaceuticals (VRTX) and Prothena (PRTA). But which of these two companies is the best option for those looking for undervalued stocks? Let's take a closer look.There are plenty of strategies for discovering value stocks, but we have found that pairing a strong Zacks Rank with an impressive grade in the Value category of our Style Scores system produces the best returns. The proven Zacks Rank emphasizes companies with positive estimate revision trends, and our Style Scores highlight stocks with specific traits.Vertex Pharmaceuticals and Prothena are sporting Zacks Ranks of #2 (Buy) and #3 (Hold), respectively, right now. The Zacks Rank favors stocks that have recently seen positive revisions to their earnings estimates, so investors should rest assured that VRTX has an improving earnings outlook. But this is just one factor that value investors are interested in.Value investors are also interested in a number of tried-and-true valuation metrics that help show when a company is undervalued at its current share price levels.The Value category of the Style Scores system identifies undervalued companies by looking at a number of key metrics. These include the long-favored P/E ratio, P/S ratio, earnings yield, cash flow per share, and a variety of other fundamentals that help us determine a company's fair value.VRTX currently has a forward P/E ratio of 14.56, while PRTA has a forward P/E of 38.13. We also note that VRTX has a PEG ratio of 1.49. This metric is used similarly to the famous P/E ratio, but the PEG ratio also takes into account the stock's expected earnings growth rate. PRTA currently has a PEG ratio of 16.37.Another notable valuation metric for VRTX is its P/B ratio of 5.10. The P/B is a method of comparing a stock's market value to its book value, which is defined as total assets minus total liabilities. By comparison, PRTA has a P/B of 8.38.Based on these metrics and many more, VRTX holds a Value grade of B, while PRTA has a Value grade of D.VRTX stands above PRTA thanks to its solid earnings outlook, and based on these valuation figures, we also feel that VRTX is the superior value option right now. Bitcoin, Like the Internet Itself, Could Change Everything Blockchain and cryptocurrency has sparked one of the most exciting discussion topics of a generation. Some call it the “Internet of Money” and predict it could change the way money works forever. If true, it could do to banks what Netflix did to Blockbuster and Amazon did to Sears. Experts agree we’re still in the early stages of this technology, and as it grows, it will create several investing opportunities. Zacks’ has just revealed 3 companies that can help investors capitalize on the explosive profit potential of Bitcoin and the other cryptocurrencies with significantly less volatility than buying them directly. See 3 crypto-related stocks now >>Want the latest recommendations from Zacks Investment Research? Today, you can download 7 Best Stocks for the Next 30 Days. Click to get this free report Vertex Pharmaceuticals Incorporated (VRTX): Free Stock Analysis Report Prothena Corporation plc (PRTA): Free Stock Analysis Report To read this article on Zacks.com click here. Zacks Investment Research