Mumbai: Brokerages Credit Suisse and JM Financial have toned down their optimism on metal stocks and believe the best part of the run-up might be over as valuations are at decade high levels and the frantic rally in Steel prices may not sustain. Credit Suisse on Wednesday downgraded Tata Steel and Jindal Steel to neutral and JSW Steel to underperform saying that risk reward is not favourable with price-to-book values at decade high levels. The brokerage said peak of the global steel prices is likely over. "Steel names are trading at a significantly higher P/B (price-to-book) than at past peaks. While there is no denying that these multiples could rise even further if demand materially surprised us on the upside in 2H CY21 (July-December), we prefer to be on the sidelines for the lack of margin of safety at current valuations,” said Credit Suisse.A revival in commodity upcycle has lifted the BSE Metal index by 61% so far this year, outperforming the BSE Sensex which is up 6.8% for 2021.