Thursday wasn't a good day for the stock market, with investors seemingly giving up on their recent optimism and focusing on some of the things that could go wrong in the current economic and geopolitical environment. Major indexes were broadly lower in the wake of new fears that stimulative monetary policy in the U.S. and Europe might not prove sufficient to prevent a global recession. Meanwhile, many market participants were paying close attention to earnings, and some companies had disappointing reports that led to significant share-price declines. Align Technology (NASDAQ:ALGN), Spirit Airlines (NYSE:SAVE), and LendingTree (NASDAQ:TREE) were among the worst performers. Here's why they did so poorly.

Align gets bent out of shape

Shares of Align Technology plunged 27% after the orthodontic device specialist released its second-quarter financial results. Growth for the period was actually reasonably robust, with top-line gains of 22.5% helping to lift earnings per share by more than 40% compared to the year-earlier quarter. International growth remained solid, with a 37% rise in shipments showing the increasing demand for Align's devices abroad. Yet even that strong growth wasn't as much as what some investors wanted to see. More importantly, Align is nervous about its expansion prospects in China, and extremely conservative third-quarter guidance suggested that earnings could actually fall next quarter -- not at all what growth-conscious investors have become accustomed to seeing from Align.

Person in white coat and blue glove handing dental appliance to smiling patient.

Image source: Align Technology.

Spirit hits turbulence

Spirit Airlines saw its stock plunge nearly 24% following its release of its Q2 financial report. Spirit said that revenue hit the $1 billion mark during the quarter, rising 19% in just the past 12 months, and adjusted net income climbed by more than half from year-ago levels. Yet some of the comments that Spirit made about its future performance cast some doubt about whether the discount airline has really gotten its momentum back. Part of the decline might well have come from the fact that Spirit's release of preliminary information earlier this month didn't seem to hint at potential future problems, and that possibility appeared to take shareholders aback today.

LendingTree wilts

Finally, shares of LendingTree dropped 16%. The online financial services specialist reported better-than-50% gains in consolidated revenue, setting a new high-water mark on that figure. LendingTree's insurance and credit card businesses kept up their positive momentum, and the weaker mortgage business showed some signs of a potential recovery. Yet even those impressive-sounding gains weren't enough to satisfy investors, especially after having seen LendingTree's stock nearly double so far this year. Going forward, shareholders fear that a downturn in consumer lending might well hit the company hard -- especially after all the capital improvements that have gotten made recently.

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