Is Protagonist Therapeutics, Inc. overvalued or undervalued?

As of 17 October 2025, the valuation grade for Protagonist Therapeutics, Inc. has moved from expensive to very expensive, indicating a significant deterioration in its valuation outlook. The company appears to be overvalued given its high P/E ratio of 60, an EV to EBITDA of 94.50, and a Price to Book Value of 4.89, which are substantially above industry norms. In comparison, Aurinia Pharmaceuticals, Inc. is fairly valued with a P/E of 20.87 and an EV to EBITDA of 12.92, highlighting the stark contrast in valuation metrics.
Despite the overvaluation, Protagonist Therapeutics has delivered impressive returns, with a year-to-date return of 100.78% compared to the S&P 500's 13.30%, and a three-year return of 838.26% against the S&P 500's 81.19%. This strong performance may reflect investor optimism, but the elevated valuation ratios suggest that the stock may not be sustainable at these levels.