Ed Zander has stepped down as head of Motorola after a string of poor sales figures.

Zander will remain as chairman until May next year and will be replaced as chief executive by Greg Brown, current chief operating officer, in January.

"We are exceedingly fortunate to have a leader of Greg's calibre, vision and experience," said Zander.

"He has been an invaluable partner and I am confident he is the right person to be the next chief executive of Motorola and lead the company through its multi-year transformation.

"Next year marks my 40th in the technology industry. This is the right time for me to move on to the next phase in my life and spend more time with my family.

"I am grateful to have had the opportunity to lead Motorola over the past four years. It has been a wonderful experience."

Zander had promised to make the company's handset business profitable by next year, but sales figures have been disappointing. The company recently lost its number two position in the market to Samsung.

Brown said in a statement: "I am privileged to become the chief executive of Motorola. This is a unique company with strong technology, people and customers.

"We have a lot to do and I am focused on building shareholder value. I look forward to working closely with Ed to ensure a smooth transition."