The stock market was somewhat mixed on Thursday, with most major benchmarks giving up most or all of their early gains by the end of the trading session. There's a lot of uncertainty about the future direction of the global economy and whether investors should expect the long-running bull market to continue indefinitely. At least at the individual stock level, there were several companies that saw significant declines in their shares. United States Steel (NYSE:X), EZCORP (NASDAQ:EZPW), and Seagate Technology (NASDAQ:STX) were among the worst performers. Here's why they did so poorly.

U.S. Steel sees a tough quarter ahead

Shares of United States Steel dropped 11% after the company released guidance for its third-quarter financial results. The steelmaker said that the market for flat-rolled steel has softened after a short period of encouraging price moves early in the summer, and a bigger drop in scrap prices than the company expected will hurt earnings from U.S. Steel's flat-rolled segment during the second half of the year. Combined with poor conditions in Europe, U.S. Steel will have to keep some of its production facilities idled, and ongoing efforts to become more efficient could result in further adjustments to its workforce. That should keep earnings under pressure at least through the end of the year, and that's far from the encouraging news investors wanted to hear.

Steel rolling out of a heating furnace.

Image source: U.S. Steel.

EZCORP makes some changes at the top

EZCORP's stock fell 12.5% after the company announced some changes at its board of directors. The pawn shop specialist replaced former executive chair Lachlan Given with Phillip Cohen, and it named Matthew Appel to serve as lead independent director of the board. Appel's role will be to act as the main point of contact between Cohen and CEO Stuart Grimshaw. With all the innovation in the fintech industry lately, short-term loan providers like EZCORP face the long-term possibility of having their business models made obsolete. Yet that'll take time, and for now, shareholders seem concerned that a new leadership team might have trouble finding the right strategy for future success.

Seagate sinks

Finally, shares of Seagate Technology lost 7%. The data storage specialist had seen gains recently, including some modest moves higher on Wednesday after it offered encouraging guidance for its fiscal first quarter. However, at today's investor day presentation, Seagate seemed to throw cold water on some of that optimism, and stock analysts appeared to lose some of their confidence in the company's future. The cloud computing revolution means that there'll be plenty of demand for data storage going forward, but that's no guarantee that Seagate will be one of the winning players in the space.