In a series of rapid-fire events Tuesday, Lexmark International announced the retirement of its longtime chief executive, named a new chief executive, beefed up its app store, and reported improved third-quarter sales and profits. But it all was for naught as the company's stock plunged 18% in early trading Tuesday.

The likely reason for the stock drop was the printer company's forecast that fourth-quarter sales aren't expected to be as rosy as stock analysts have been predicting, according to media reports.

Paul J. Curlander, currently chairman and CEO of Lexmark, will retire from the company in the spring. Paul Rooke was named to succeed him. Curlander has been with the company from its early days when it was a unit of IBM, and for nearly 20 years after Lexmark spun off from IBM, for a grand total of more than 35 years. "Under Paul's leadership, Lexmark has established itself as a world leader in imaging products, solutions, and services," said Jean-Paul Montupet, Lexmark's presiding director, in a statement.

Rooke, also a longtime Lexmark employee, most recently was executive VP and president of the firm's imaging solutions division.

The company's third-quarter profits rose sharply from $72 million, compared to third-quarter earnings of $10 million in 2009. Revenue was up from $958 million to $1.02 billion in the same period. The company's prediction of a drop in anticipated sales revenue, however, appeared to spook investors who drove down the price of Lexmark's stock.

On Monday, Lexmark unveiled its software development kit, which it is using to attract software developers to create apps for its inkjet all-in-one SmartSolutions printer base. Lexmark is promoting SmartSolutions as a way to create powerful workstations that take advantage of the capability of Lexmark printers to print, scan, copy, and fax.

The new apps will be written in Adobe's Flash technology and will be added to some 60 existing apps already created by Lexmark and its partners. Lexmark executives have said they plan to have a revenue sharing plan in place for software developers who write applications for Lexmark products.