Steel yourself: The best-performing stock in the broad S&P 1500 index probably isn't one you'd expect.
Shares of U.S. Steel have risen more than 100 percent this year, for a clean double. This as the stock has benefited from preliminary U.S. duties on certain steel products, which could improve the supply/demand dynamics.
To be sure, this has not been a winning trade over the long term. U.S. Steel has still lost two-thirds of its value over the past five years. And on the credit side, the stock's bonds are rated sub-investment-grade by the three major ratings agencies.
After the stock's tremendous gains, it may about time to take some profits, says Erin Gibbs, equity chief investment officer of S&P Investment Advisory.
"I see the stock as fully valued and I do not see more upside," Gibbs wrote to CNBC. Even if the duties help, the stock will still have to contend with large import levels of steel into the U.S., troubles for the domestic manufacturing sector, a strong U.S. dollar that weighs on commodity prices, and low energy prices that reduce the demand for steel products necessary in oil exploration and production, Gibbs points out.