Intel shares plunged nearly 9 percent Friday after the company cut its forecast for 2019 and warned investors of a “concerning” outlook.

Intel shares closed down $5.18 at $52.43, wiping out an astonishing $23 billion in market value and erasing weeks of gains for the stock. The chipmaker said weak prices for memory chips, disappointing sales to data centers and the weak Chinese economy are undermining sales.

The stock was down nearly 11 percent early in the day but recovered slightly after The Wall Street Journal reported Intel is shopping its 5G modem business to Apple and other companies, and might receive billions of dollars if it finds a buyer.

Intel now expects sales to decline by almost 3 percent in 2019, which would be the company’s biggest revenue drop since the Great Recession. And Intel indicated the slide is already under way: it expects sales in the current quarter will be down 8 percent from the same period last year.

At the same time Intel is still working to deliver its next generation of 10 nanometer microprocessor, already years behind schedule. Rivals are racing ahead, erasing Intel’s technology leadership.

And the company’s factories are still unable to meet customer demand, in part because capacity has been set aside for 10nm chips that aren’t yet ready for prime time.

“Ongoing 10nm delays emphasize Intel's loss of core competitive advantage, while soft demand and increasing competition remain concerns,” wrote Weston Twigg, analyst for KeyBanc Capital Markets in Portland, in a note to clients. “We're lowering our estimates meaningfully, and we see little near-term upside.”

Intel said it expects the second-half of the year to be better but Stacy Rasgon, an Intel skeptic who follows the company for Sanford C. Bernstein, is dubious. He said Intel’s forecast for late in the year appears unrealistically optimistic, projecting “the strongest (second-half) ramp we’ve ever seen.”

“We suspect the (second half of 2019) is going to get interesting as the dynamics of potential demand recovery play off against the company's own acknowledgement of increasing competition,” Rasgon wrote.

Other analysts were more sanguine. David Wong with Instinet kept his $65 target pricing on the stock, noting “the company’s solid profitability and its leadership in what we think will be some of the most promising semiconductor end markets,” which include artificial intelligence, self-driving cars and data centers.

This article has been updated with Intel’s closing price.

-- Mike Rogoway | twitter: @rogoway | 503-294-7699