US Steel plunges 25% as the sector championed by Trump just last week completely rolls over

After a rally last week in the wake of President Donald Trump's announcement that he would be kick starting a probe into imported steel, steel stocks tumbled Wednesday as weak earnings and slashed guidance from United States Steel (NYSE:X) sent worries through the sector.

U.S. Steel reported a quarterly loss of $1.03 per share, according to Thomson Reuters. That was quite a miss, as analysts polled by were expecting a quarterly profit of 35 cents per share. The company also slashed guidance, expecting full-year 2017 earnings of $1.50 per share, half the Street's expected figure of $3.05 per share.

Five-day performance of X

Source: FactSet

Released after the bell Tuesday, the earnings report sent U.S. Steel's stock into a 26 percent nosedive Wednesday.

"While our segment results improved by over $200 million compared with the first quarter of 2016, operating challenges at our FlatRolled facilities prevented us from benefiting fully from improved market conditions" U.S. Steel CEO Mario Longhi said in a release. "However, we continue to be encouraged by the strength of our European business and we are also seeing improving energy markets."

The sector had substantial gains last week when President Trump said he was going to take a closer look at foreign steel imports deflating U.S. prices. But U.S. Steel's weak report is making waves throughout the industry, as other steel companies saw dips in action on Wednesday.

More From CNBC

• Despite market highs, it's not too late to get into the game, experts say
  

• Sell in May? Yes, but traders may want to hang around for the thrill ride
  

• Breakingviews: Twitter will need more than just user growth