Is Plains All American Pipeline LP overvalued or undervalued?

As of 4 May 2021, the valuation grade for Plains All American Pipeline LP moved from risky to very attractive, indicating a significant improvement in its valuation outlook. The company appears undervalued, supported by a P/E ratio of 9, which is notably lower than its peer Western Midstream Partners LP at 11.04, and an EV to EBITDA ratio of 7.79 compared to Antero Midstream Corp.'s higher 12.89. Additionally, the Price to Book Value stands at 1.27, suggesting that the stock is trading below its book value relative to peers.
In terms of returns, Plains All American Pipeline LP has shown a 46.92% return over the past three years, although it has underperformed against the S&P 500, which returned 70.41% in the same period. This performance, alongside its attractive valuation ratios, reinforces the notion that the stock is currently undervalued relative to its peers and the broader market.