Wall Street financier Carl Icahn, perennial provoker of the managements of underperforming companies, has renewed his pressure on Motorola in the wake of the announcement that chief executive Ed Zander would be replaced at the top by Greg Brown.

In an interview reported in Thursday's Wall Street Journal, Icahn said that breaking up Motorola would likely improve the company's long-suffering finances. Icahn noted that Motorola's handset operation -- the company's biggest business with $39 billion in sales -- isn't contributing much to Motorola's stock price. The company's mobile phone market share has been sliding in recent years with the result that it has helped drag Motorola's stock down with it.

"The point is that if the handset business was spun off, with over $20 billion in revenue in a growing industry, it is obviously worth a great deal," Icahn said, suggesting that the action could boost Motorola's stock price. The company, however, has ignored calls for its breakup and has said it remains committed to its current strategy to improve its business.

The company has disposed of major operations in recent years while making various strategic acquisitions, some small, some large. In particular, Motorola has suffered in comparison with Nokia, which has its main focus on mobile phones; Nokia's handset market share -- and stock price -- has surged in recent years and it now accounts for nearly 40% of the market for mobile phones.

Icahn, who has taken note of Motorola's large cash reserve, has suggested the company could boost its stock price by repurchasing its stock. In a recent report, Icahn was listed as Motorola's third-largest stockholder, owning 3.3% of its stock.