When the dust settles on the 2018 holiday-shopping season, it might still look like the spending boom many expected. But in the meantime, early results from big public companies are bringing long-held worries about the industry back to the surface.

Investors entered the holidays with both optimism and trepidation, knowing that this might be the last hurrah of the economic recovery — a kind of peak Christmas. Thursday's jarring results cast doubt on that premise, as a strong economy and high consumer confidence failed to translate into a standout year-end for every store. For those lucky chains that did sidestep lackluster sales, there's a growing concern that all the promotions and free shipping ate into profits.

As the results start rolling in, the early signs are disquieting. Department stores Macy's and Kohl's disappointed. Bookseller Barnes & Noble boosted sales, but warned earnings might suffer as a result of its discounting. And while Target beat sales estimates, analysts warned that profit could be another story.

Slowing sales and more pressure on profit margins will no doubt increase the divide between the winners and losers in the retail industry. Over the past two years, a slew of bankruptcies, including high-profile chains such as Toys "R" Us Inc. and Sears Holdings Corp., had some calling this era a "retail apocalypse." But those struggles occurred during a frothy environment — 2017 and 2018 was the best two-year stretch for retail sales during the economic recovery. So what happens if consumers do pull back or become even bigger bargain hunters?

"Ultimately, promotions and deals are back," said Simeon Siegel, an analyst for Nomura Instinet. "Today is more of a sign of retail health, or lack thereof, than consumer health. There was a false sense of structural improvement."

The season started strong. Black Friday weekend, the official start of the season, saw more than 165 million U.S. consumers shopping, but there are signs spending waned after an initial surge. Macy's CEO Jeff Gennette said its sales momentum during the holidays weakened in mid-December and "did not return to expected patterns" until Christmas week.

"Investors got ahead of themselves after Black Friday," said Gabriella Santaniello, founder of retail consulting firm A Line Partners. "This is not a case of a rising tide lifts all boats."

Retailers sold off Thursday, with the SPDR S&P Retail ETF sinking as much as 4.2 percent. Macy's emerged as the S&P 500's worst daily performer, damping the rest of the market. The results also raised concerns about the strength of the U.S. consumer and what the year ahead will look like for the retail industry.

"If Macy's can't deliver in a stronger consumer environment, then what does that mean for its future?" said Poonam Goyal, an analyst at Bloomberg Intelligence. "Can it outperform if the economy gets a little weaker?"

Companies are already facing the potential of more tariffs and continued cost increases for labor and transportation. Toss in a disappointing Christmas that weighs on profit, and that may create a "double whammy," which could slow down hiring, according to David Schick, director of research for Consumer Edge Research.

"We are seeing broad evidence that the 2018 holiday season was likely better early than late," Schick said. "This has implications for margins into 2019."

Discounter Target reported same-store sales growth of 5.7 percent, topping estimates of about 5 percent. But it didn't increase its fourth-quarter sales or earnings guidance and only gave a vague forecast for this year, saying it would deliver "profitable growth."

"Target is doing an excellent job driving sales growth," Simeon Gutman, a Morgan Stanley analyst, said in a research note. "However, this growth is coming at the expense of profitability." Plus, this year will only be more difficult with a "weaker consumer spending backdrop."