CHICAGO — Motorola Inc.'s two-year, Razr-fueled resurgence in the global cell-phone market was in trouble yesterday after the company warned of disappointing sales and earnings from the key holiday selling season.

Investors sent the company's stock down sharply amid a consensus that the trendsetting Razr has lost its buzz in the marketplace and Motorola's efforts to come up with a new killer product have so far not paid off, hindered by stiffening competition.

Motorola's pre-announcement Thursday night of worse-than-anticipated fourth-quarter results made it two straight quarters that the company has fallen short of Wall Street expectations.

It also threatens to end eight consecutive quarters of market-share gains for a company that, despite improving to a 22 percent share from 16 percent in 2004, remains far short of recapturing the lead it held in the 1990s from Finland's Nokia Corp.

Shares fell $1.61, or 7.83 percent, to close at $18.94 on the New York Stock Exchange after sinking as low as $18 earlier in the session, matching their lowest price since July 2004.

Analysts said the news raises questions about Motorola's strategy, underscoring that recent market-share gains came largely by selling less profitable phones in emerging markets as the Razr's appeal fades.

"We believe that the issues are not a one-time hiccup but rather a reflection of a weak portfolio that struggles to replace a successful Razr model," Merrill Lynch analyst Tal Liani wrote in a note to investors.

Motorola's reliance on the ultra-slim Razr and its variations to carry it through another holiday season clearly backfired, some said.

"It's becoming a tired product that's heavily discounted, especially in the U.S. market," said Kenneth Leon, an analyst for Standard & Poor's Equity Services. He said other recently introduced products, such as the Krzr and Slvr, "don't appear to have the buzz or the sales traction that we expected" and that sales of the Motorola Q smartphone, its challenger to the Blackberry, may be slowing.

Motorola isn't expected to give full details of its problems until it reports quarterly results on Jan. 19.

In its announcement, it blamed only an "unfavorable geographical and product-tier mix of sales" for causing it to fall short of estimates despite a solid 66 million units in mobile device sales, up 48 percent from a year earlier.

The Schaumburg, Ill.-based company said it now expects to earn 13 to 16 cents per share, including about 10 cents per share in charges, on sales of $11.6 billion to $11.8 billion. Those numbers are well off the consensus estimates of analysts surveyed by Thomson Financial for a profit of 39 cents per share on sales of $12 billion.

"We are very disappointed with our fourth-quarter financial performance," said Ed Zander, chairman and chief executive, "but we remain committed to the strategic direction and long-term financial targets we discussed at our annual analysts' meeting in July 2006."