$X is one of biggest losers #stocks today. read more:

United States Steel Corporation (symbol: X) was one of the worst losers of
the trading day today (2015-12-23), losing -4.84%. The number of shares
that changed hands was 21,716,659, or about 2 times the average daily
volume in the stock.
The closing price was $8.66, amounting to a market cap of $1,270,000,000,
about -68.75% off the highest price in the last 12 months. The stock has
been trading at a range between $6.8 and $27.71.
X is in the Steel/Iron Ore industry, part of the Basic Industries sector.